LANSING, Mich. – During a rally of 300 people here Monday afternoon, Rick Santorum said gas prices caused the 2008 recession and he suggested President Barack Obama is intentionally causing unemployment.

“The bubble burst in housing because people couldn't pay their mortgages because we're looking at $4-a-gallon gasoline,” Santorum said. “And look at what happened – economic decline."

After the event, the former Pennsylvania senator hedged his comments a bit. "I think they're a contributing factor," he said, shaking hands with voters. "Obviously there are a lot of factors that go into it but I think that was one of them."

Santorum and former Gov. Mitt Romney have stumped across the Wolverine State trying to convince voters that they are the true conservative in the race. Now, one day before the Michigan primary, Santorum has shifted his tough talk to President Barack Obama.

"Look at any map or chart of standard of living in a country, and then look at the availability of cost of energy – the lower the energy cost, the higher the standard of living,” Santorum said. “Now we are deliberately lowering our standard of living, deliberately causing unemployment. Why would a president do that?"

His answer Monday, as it has been at all his stops in the Rust Belt states, is that Obama is putting the environment ahead of people.

"He’s a perfectly nice man," Santorum said of Obama. "He just has a very different view of America. And let’s be honest, he is doing a pretty effective job of promoting that view and passing legislation and regulations that are consistent with his view of what America should be like.”

Santorum also targeted Romney’s record and called on the crowd for their support tomorrow.

"To be attacked on television as someone who is not an authentic conservative by a Massachusetts governor is a joke," Santorum said to laughter. "Michigan, you have the opportunity to stop the joke."

TRAVERSE CITY, MICH – Returning to Michigan after a brief trip to Florida for the rained-out Daytona 500 race, Mitt Romney began his closing arguments Sunday night, telling an audience of Michiganders that he needed their help. He pressed them to help him create a new national movement.

"I need you guys to get out and vote," Romney told an audience of more than 500 in this town on the Michigan's northwestern edge.

"I need your help. I want us to take that first step towards a better tomorrow. I want us to restore the greatness of America," Romney said.

Michigan has assumed an unusual importance in the state primary. Romney, the son of a three-term Michigan governor, and who was born and raised in the state, was presumed to clinch the nomination with ease. But recent polls show Romney in a dead heat with former Sen. Rick Santorum.

Santorum also visited Traverse City, a town of roughly 14,000 today. He drew a smaller crowd, about 250 people, at a campaign stop this afternoon.

Gus Batsikouras, an automobile sales manager, and his wife Sandra Batsikouras attended both candidates’ events. He wanted to test-drive both candidates in person.

Batsikouras, who supported Romney in the 2008 primary here, told NBC News before the Romney event that he hadn’t made a decision.

"They can say they have the greatest product out there, but unless you test-drive it, you'll never know," Batsikouras said. "I want a concrete plan of action for what he's going to do when he gets into office."

Although he voted for Romney four years ago, Batsikouras said he had reservations about the former Massachusetts governor that had little to do with Santorum. He said his main concerns are energy, national defense and the economy.

"We're not sure who is going to show up – which Romney is going to show up," Batsikouras said. "Is he going to hold true to what he's saying? I still need to figure that out."

Following Romney's address, in which the candidate addressed Batsikouras' concerns: Energy (build the Keystone Pipeline System), national defense (increase shipbuilding, add 100,000 more troops) and the economy (a 20-percent tax cut across the board), the couple was impressed but not sold.

"My only knock against him is he wasn't very specific He's still generalizing things," Batsikouras said. "Bottom line is how are they going to execute?" Batsikouras said. "Both [Santorum or Romney] will do a fine job. No doubt about that."

Less than a week before Tuesday’s crucial Republican presidential primary in Michigan, a new NBC News/Marist poll shows Mitt Romney and Rick Santorum locked in a statistical tie, while a separate NBC/Marist survey shows Romney comfortably leading in Arizona, which holds its primary the same day.

In Michigan – which has turned into a make-or-break contest for Romney – the former Massachusetts governor gets the support of 37 percent of likely GOP primary voters, including those who are leaning toward a particular candidate.

NBC-Marist poll results: Michigan | Arizona

Santorum, the former Pennsylvania senator, gets 35 percent, and he’s followed by Texas Rep. Ron Paul at 13 percent and former House Speaker Newt Gingrich at 8 percent.

NYT: GOP campaigns grow more dependent on 'super PAC' aid

“Michigan is neck and neck,” says pollster Lee Miringoff, director of the Marist College Institute for Public Opinion, which conducted both surveys.

But in Arizona, Romney is on safer ground: He receives the support of 43 percent of likely GOP primary voters, Santorum gets 27 percent, Gingrich 16 percent and Paul 11 percent.

And looking ahead to November’s general election, President Barack Obama enjoys a double-digit edge over his closest GOP competition in Michigan (a state Republicans are hoping to target), while he’s trailing the leading Republicans in Arizona (which the Obama camp wants to put into play). 

Romney vs. Santorum ideological breakdown
In both states, support for Romney and Santorum breaks down along ideological lines, as well as whether voters have already cast their ballots.

In Michigan, Santorum leads Romney among self-identified Tea Party supporters, 48 to 29 percent, and those who describe themselves as “very conservative,” 59 to 20 percent.

Michigan voters: Santorum connects better than Romney

Yet among those who don’t support the Tea Party, Romney is ahead by more than 20 points, 45 to 24 percent.

And among those who have already voted absentee in Michigan – 16 percent of likely GOP voters – Romney leads Santorum, 49 to 26 percent.

NYT: After auto industry bailout, Detroit fallout trails Romney

The same ideological pattern is true in Arizona, although Romney performs much better with the most conservative voters there than in Michigan. 

And among those who have voted early or absentee in Arizona – more than half of all likely Republicans voters in the poll – Romney holds a 30-point advantage over Santorum, 52 to 22 percent.

Obama leads in Michigan, trails in Arizona
Turning to the general-election race in November, Obama leads Romney in Michigan by nearly 20 points among registered voters, 51 to 33 percent, with 15 percent undecided.

Against Paul, the president’s lead is 22 points (53 to 31 percent); against Santorum, it’s 26 points (55 to 29 percent); and against Gingrich, it’s 28 points (56 to 28 percent).

What’s more, 51 percent of registered Michigan voters approve of Obama’s job; 63 percent of them believe the auto industry bailout was a good idea (including 61 percent of independents and 42 percent of likely GOP primary voters); and a majority think the president deserves credit for the auto industry’s recovery.

But Arizona is tougher territory for the president, whose approval rating among registered voters in the state is just 38 percent.

NYT: Obama offers to cut corporate tax rate to 28%

In hypothetical match-ups, Obama trails Romney by five points (40 to 45 percent); Santorum by three (42 to 45 percent); Paul by 2 points (41 to 43 percent); yet he leads Gingrich by five (45 to 40 percent).

The NBC/Marist survey of Michigan was conducted Feb. 19-20 of 3,149 registered voters (margin of error of plus-minus 1.8 percentage points) and 715 likely Republican primary voters (plus-minus 3.7 percentage points).

The NBC/Marist survey of Arizona also was conducted Feb. 19-20 of 2,487 registered voters (plus-minus 2.0 percentage points) and 767 likely GOP primary voters (plus-minus 3.5 percentage points).

GRAND RAPIDS, Mich. – In back-to-back appearances before two separate audiences under the same roof here tonight, Mitt Romney made part of his Michigan strategy clear: Pick a fight with "big labor" by labeling their support of President Barack Obama as "crony capitalism."

To a group of business leaders who had gathered for a roundtable discussion, Romney said that Obama’s bailouts of Chrysler and General Motors were designed to "foster the interests of organized labor."

"The President finally came around to my own view that Detroit needed to go through managed bankruptcy,” Romney said. “But he gave the companies to the UAW (United Auto Workers) when he was finished with the process. That again is something which I think is consistent with the fact that he got a lot of money from organized labor and felt that he should give them a favor."

Romney repeated his attack on Obama and the auto workers union during a rally that followed the roundtable. He vowed to limit the power of "union bosses."

"He got hundreds of millions of dollars from labor bosses for his campaign, and so he's paying them back in every way he knows how,” Romney said. "I've taken on union bosses before, and I'm happy to take them on again."

While Romney has said he does not oppose all unions (he often cites the carpenters' union as an example of one he likes), the strategy of taking on labor unions is not without risk in Michigan, where 12 percent of the state's workforce belongs to a union, according to government records.

Building on a theme, Romney's campaign announced a conference call entitled “Rick Santorum's Defense of Big Labor and Big Spending."

Romney balanced his attacks on labor with cheery anecdotes about his upbringing in Michigan.

"I visited every county in Michigan, I think more than once, on my dad's campaign and my mom's campaign," Romney reminisced onstage at the rally. "I've gone to the country fairs. So I didn't always see the best of each county but I saw every county in this extraordinarily beautiful state. I love Michigan."

NBC ad tracking sources show the personal may also be political – Romney’s campaign has put $1.2 million toward advertising in Michigan – more than the deep-pocketed pro-Romney super PAC Restore our Future has spent here to date. His first television ad in the state touts his childhood in the Wolverine State.

Tomorrow, Romney will accept the endorsement of the state's Republican governor, Rick Snyder, campaign and GOP sources tell NBC News. Snyder, a former businessman who calls himself "one tough nerd," will appear alongside Romney at a midday event in Farmington Hills.