Capitol Hill will play host to a springtime clash over gun rights, as lawmakers prepare to take up significant gun control legislation for the first time in years. 

The Senate will take up a new bill next month intended to require background checks for every firearm purchase in the country — and proponents of the legislation are girding for a major political showdown against supporters of gun rights and its principal advocacy group, the National Rifle Association. 

New York City Mayor Michael Bloomberg has emerged as one of the most forceful national backers of stricter gun laws, and this weekend launched a $12 million television ad campaign meant to pressure wavering senators to support the new legislation when they return from their holiday break.

"We're trying to do everything we can to impress upon the Senators that this is what the survivors want, this is what the public wants," he said on NBC's "Meet the Press" on Sunday. He added later: "If 90 percent of the public want something, and their representatives vote against that, common sense says, they are going to have a price to pay for that."

But his push has been met with strict resistance by the NRA, which has dug in against stricter controls on guns since last December's massacre at an elementary school in Newtown, Conn., the catalyzing event for President Barack Obama's renewed push for new gun laws. 

"He can't spend enough of of his $27 billion to impose his will on the American people," said Wayne LaPierre, the NRA's CEO and executive vice president, of Bloomberg's new advertising effort. "He can't buy America."

Already, advocates of stricter gun laws have suffered setbacks due to the NRA's resistance. Senate Majority Leader Harry Reid, D-Nev., said this week that he would move forward with legislation following the holiday recess, but said it would exclude a reinstatement of the ban on assault weapons, which appears to lack sufficient support to move forward in the Senate. But Democrats will seek a vote on the ban in the form of an amendment, laying down a political marker — which Bloomberg said he would be watching closely.

"I don't think we should give up on the assault weapons ban," he said. "But clearly, it is a more difficult issue for a lot of people … It may be just that people have different views about assault weapons than they do about background checks."

But even the proposed expansion of background checks is far from assured passage in Congress. Failing to advance this more modest gun control would be a blow to efforts to advance gun controls, even with a high-profile event like the Newtown massacre providing an impetus for action.

LaPierre derided the proposal on background checks as little more than "a speed bump for the law-abiding." Though the NRA had supported the background check system in the past, LaPierre said it was "not fair," "not accurate" and "not instant" in practice.

Days after lawmakers sidelined a proposed assault weapons ban, Vice President Joe Biden and New York City Mayor Michael Bloomberg on Thursday offered a stern warning to Congress: there are still political consequences for opposing the measure.

"Even though restrictions on military-style weapons will not be part of the bill that goes to the floor of the U.S. Senate, it will get a vote by the full Senate as an amendment to the bill. And everyone’s going to have to stand up and say yea or nay, and then the rest of us have to decide just how we feel about people and their stands," Bloomberg said at a New York press conference with Biden and several family members of children killed in last year’s Sandy Hook Elementary shooting.

Bloomberg urged members of the public to tell congressional opponents of the gun control measure that they will “support whoever runs against you, no matter who they are.”

"Congress just has to get some courage and it's up to us as Americans and as fellow human beings to give them that courage," he said.

For the billionaire mayor, that “courage” also means “cash.”  

Bloomberg has already put millions behind his efforts to elect lawmakers who support gun control -- and his aides say he plans to use millions more on ads to sway those who might vote against it.

Biden, in New York to meet with Bloomberg just days after the Senate dropped the assault weapons ban from its gun bill, insisted that public opinion has shifted on gun restrictions -- and that the political pressure from the gun lobby has been overstated.

"It must be awful, being in public office and concluding that even though you might believe you should take action that you can't take action because of the political consequence you face. What a heck of a way to make a living. What a heck of a way to have to, have to act," Biden said. "The message I want to get across, Mr. Mayor, is the risk does not exist as is exaggerated today."

A suite of new gun control restrictions is winding through Congress, with Senate Democrats set to outline a package that could include new school safety measures, universal background checks for gun buyers and tougher penalties for straw purchasing and gun trafficking. 

But it's already clear that the politics of gun control are still difficult -- and as the Newtown massacre fades into the national memory, it's only going to get harder. Senate Majority Leader Harry Reid this week informed California Sen. Dianne Feinstein that the assault weapons ban she's championed for decades won't be included in the bill, all but dooming its chances.

Senators will still vote on the ban as an amendment to the bill, allowing advocates the chance to see who voted against it and giving red state Democrats the chance to show they're opposing Obama's gun restrictions. There will be a second, separate vote on an amendment to ban high-capacity magazines.

This story was originally published on Thu Mar 21, 2013 1:44 PM EDT

Vice President Joe Biden argued Wednesday that Democratic voters in yesterday’s special Democratic congressional primary in Illinois illustrated that there is a larger national mandate for tighter gun restrictions.

“The voters sent a message last night, not just to the NRA but to the politicians all around the country by electing Robin Kelly, who stood up and stood strong for gun safety totally consistent with our Second Amendment rights,” Biden told a gathering of state attorneys general in Washington D.C.

Kelly, a former state representative, won decisively over U.S. Rep. Debbie Halvorson, a Democrat who at one time had been favored to win the Chicago-area seat. But Halvorson faced over two million dollars’ worth of negative advertising funded by pro-gun control billionaire Mayor Michael Bloomberg, who attacked her for an “A” rating from the National Rifle Association.

The congressional district, which is heavily Democratic, includes some of Chicago's South Side neighborhoods as well as suburban areas south of the city.

Biden said Kelly’s decisive victory sent an “unequivocal signal” in the first major electoral contest since the shootings at an elementary school in Newtown, Conn.

“The message is there will be a moral price as well as a political price to be paid for inaction,” he said.

After meeting with Biden today, Bloomberg said he believed the race showed that support for stricter gun laws won't hurt candidates.

Bloomberg said the White House should reach out to members of Congress to explain "why their vote could make a difference and why all the polls show that they will not be disadvantaged the next time they run."

"Quite the contrary," he added. "They will have this as a feather in their cap and be able to say next time they run ‘when the going was tough, I stood up for you.’”

NBC's Kasie Hunt contributed to this report. 

New York Mayor Michael Bloomberg made a personal six-figure contribution to Americans for Responsible Solutions, the political action committee run by former Rep. Gabrielle Giffords (D-Ariz.) and her husband Mark Kelly, a source close to the mayor tells NBC News.

As First Read reported earlier, Americans for Responsible Solutions will spend six figures to air a new ad beginning this week. The ad will air in DC and in cities represented by congressional leaders: San Francisco (Nancy Pelosi), Cincinnati (John Boehner), Louisville (Mitch McConnell), and Las Vegas (Harry Reid).

Bloomberg has his own group, Mayors Against Illegal Guns, that's pressing Congress to take steps to reduce gun violence. Bloomberg's own Independence PAC has spent nearly $1 million on ads attacking former Democratic Rep. Debbie Halvorson for her "A" rating from the National Rifle Association.

Halvorson is locked in a Democratic primary for former Rep. Jesse Jackson's seat in Illinois.

Friday's school shooting in Connecticut prompted a renewed effort by lawmakers to re-evaluate gun rights, as a top Democrat vowed Sunday to introduce new legislation on the first day of the new Congress next year.

The massacre at an elementary school in Newtown, Conn. left 28 dead, including 20 students, seven adults and the suspected shooter, leading proponents of gun control to redouble their efforts to seek new regulations. New York City Mayor Michael Bloomberg, an outspoken advocate of gun control, said the issue should now be atop President Barack Obama's second term agenda.

To that end, California Sen. Dianne Feinstein, D, said she intended to introduce a gun control bill on the first day of the next Congress. Paired with a twin version in the House, Feinstein's law would take aim at limiting the sale, transfer and possession of assault weapons, along with the capacity of high-capacity magazines. 

"It can be done," she said on NBC's "Meet the Press." The senator, a proponent of gun control, said she expected Obama to offer his public support for the law. 

A federal ban on assault weapons, first passed in 1994 and signed by President Bill Clinton, expired in 2004. And while Obama has said he favors its reinstatement, the administration has hardly thrown its weight behind such a proposal during his first term. 

The especially grisly shooting in Connecticut — which follows several other high-profile shootings at a movie theater in Aurora, Colo., and outside a Sikh temple in Wisconsin — might now serve as a catalyzing moment in that dormant gun debate. 

"We're going to have to come together and take meaningful action to prevent more tragedies like this, regardless of the politics," Obama himself said on Friday in the aftermath of the Newtown shooting. 

Outspoken proponents of gun control, like Bloomberg, have now begun to pressure the president to speak out more forcefully on the issue. 

"It's time for the president to stand up and lead and tell this country what we should do," said the New York City mayor. "This should be his No. 1 agenda."

There are indications that some of the most commonly discussed measures to rein in weapons enjoy some degree of public support. An early August CNN/ORC poll, conducted in the aftermath of the Colorado and Wisconsin shootings, found varying levels of public support for different gun control proposals. Fifty-seven percent of adults, for instance, said they favored a ban on the manufacture, sale and possession of assault weapons, and 60 percent said they supported a ban on the possession of high-capacity ammunition clips. 

But gun owners' groups, like the National Rifle Association, could prove a significant political obstacle to moving any such proposals through Congress. The NRA — which endorsed Obama's Republican opponent, Mitt Romney, during the presidential campaign — remains a formidable political force. The group could target, for instance, Democrats from rural or centrist districts and states for defeat if they were to vote for such a law. 

Bloomberg argued otherwise. "There is this myth that the NRA is so powerful," he said. "Today the NRA's power is so vastly overrated."

In the meantime, the mayor said, Obama could take action through executive orders to strengthen and update the background check system and more aggressively enforce existing laws. 

On Sunday, the president will travel to Newtown to comfort victims' families and thank first responders for their efforts. Obama will also speak at a vigil this evening.

New York City Mayor Michael Bloomberg endorsed President Barack Obama on Thursday, invoking Hurricane Sandy and the president's work to address climate change.

As New York reels from the fallout of this week's hurricane, which caused 37 deaths in the city, Bloomberg said Obama was better-suited than Republican presidential nominee Mitt Romney to curb carbon emissions.

"The devastation that Hurricane Sandy brought to New York City and much of the Northeast – in lost lives, lost homes and lost business – brought the stakes of Tuesday’s presidential election into sharp relief," Bloomberg wrote. "Our climate is changing. And while the increase in extreme weather we have experienced in New York City and around the world may or may not be the result of it, the risk that it might be – given this week's devastation – should compel all elected leaders to take immediate action."

The three-term mayor and billionaire further lauded Obama for taking "major steps to reduce our carbon consumption." In turn, Bloomberg said that on the issue of climate change, Romney had "reversed course, abandoning the very cap-and-trade program he once supported."

A former Republican who has since declared himself independent, Bloomberg did not make an endorsement for president in 2008. He cited other issues, including Obama's health care reform law, approach to abortion rights and support for same-sex marriage, in reaching his conclusion.

Eduardo Munoz / Reuters

New York Mayor Michael Bloomberg speaks to the media during a news conference about Updates to New Yorkers on Preparations for Hurricane Sandy in New York, October 26, 2012.

"I'm honored to have Mayor Bloomberg's endorsement. I deeply respect him for his leadership in business, philanthropy and government, and appreciate the extraordinary job he's doing right now, leading New York City through these difficult days," Obama said in a statement.

The endorsement comes, though, amid one of the worst storms to batter the New York area in recent history, Obama's response to which has drawn him plaudits from a bipartisan array of figures, including New Jersey Gov. Chris Christie (R).

Obama also added: "While we may not agree on every issue, Mayor Bloomberg and I agree on the most important issues of our time - that the key to a strong economy is investing in the skills and education of our people, that immigration reform is essential to an open and dynamic democracy, and that climate change is a threat to our children's future, and we owe it to them to do something about it."

*** UPDATE *** An Obama campaign official told NBC's Kristen Welker it's impossible to know the impact of the endorsement but called it a "net positive" citing the fact that Bloomberg has an audience of independent-minded voters. Campaign officials say they were made aware the of the endorsement before Bloomberg announced it.  

One Republican operative suggested the endorsement could actually hurt the president calling Bloomberg "the most anti-gun politician" in the country. The operative predicted the endorsement won't play well in states with heavy-hunting populations like, Wisconsin, Pennsylvania or Minnesota.  "So congratulations, Mr. President," the operative said sardonically. 

New York City Mayor Michael Bloomberg met Tuesday morning with Mitt Romney in the Manhattan offices of the mayor's foundation.

NBC News confirmed news that the independent mayor met with Romney, who's spending a busy day in the city. A source in the mayor's office said that Bloomberg advocated for his usual agenda of gun control, budget reform, education, the economy and the manner in which the federal government treats cities.

A source described the meeting between the two as "friendly," though it yielded no endorsement. It's unclear whether he'll do so at all this year, and Bloomberg maintains ties to the Obama administration; he golfed last Friday with Vice President Biden.

The stop with Bloomberg was part of a busy morning for Romney in New York City. His schedule included a CBS interview this morning, his Bloomberg meeting, attending a memorial for the late journalist Mike Wallace, and a meeting soon with former NYC Mayor Rudy Giuliani (who recently endorsed Romney).

UPDATE, 1:07 p.m.: Romney's day will continue in Philadelphia, where he'll host a fundraiser.

New York City Mayor Michael Bloomberg isn’t letting anyone -- on either side of Pennsylvania Avenue -- off the hook after the Super Committee’s failure to reach a bipartisan deficit deal this week.
 
“There’s no heroes here,” Mayor Bloomberg said today on MSNBC’s "Andrea Mitchell Reports."
 
“In the last 10 years, the government’s revenues have gone up 15%," he said. "The government’s expenditures have gone up 80%. That was done during Republican and Democratic administrations, it was done by the White House and Congress.”

Bloomberg added, “Everybody created this problem, and now they can’t even figure out a way to save $1.2 trillion or one year’s deficit over the next 10 years.”
 
But the Super Committee is not entirely to blame, the mayor said. President Obama could help break Washington’s political gridlock by using his veto power.
 
“There is one answer to this: All the president has to do, and I’m not trying to hold him more responsible but he is the chief executive, he was elected to lead this country. All he's got to do is stand up and say, ‘I will veto any extension of any of the Bush-era tax cuts. Everybody. Not just the rich, but everybody.’ And that takes taxes off the table. Then the Republicans don't have an issue, and they can start working with the Democrats with coming up with intelligent cuts,” he said.

So what about a third-party presidential run for the Mayor? Not this time, he answered.
 
“I have a commitment to the public to serve four years. I'm going to honor that commitment. I've got a great job. I love it every day. That's what I'm going to do.”