Rick Santorum leads in polls, but he's spent much of the last two days defending provocative comments. ... A Romney Arizona co-chairman -- and hard-line immigration sheriff -- quits after a sex scandal erupts ... Romney asks Trump to give him air cover ... And half of all GOP primary ads have been negative.

1. Santorum leads nationally, in states…
Rick Santorum is maintaining the lead in national polls. His margin in the ever-fluctuating Gallup Daily Tracking poll expanded to 10 (36%-26% over Mitt Romney) today.

Another poll conducted by Gallup for USA Today shows Santorum up six, 50%-44%. (By the way, two-thirds of Republicans in that poll say they oppose a so-called “brokered” convention.)

National polls in primaries mean almost nothing. But as Super Tuesday March 6th approaches with 11 states across the country voting, national polls will mean a little bit more.

In Oklahoma, the Sooner Poll shows Santorum up 16 points, 39%-23%, with Newt Gingrich -- not Romney -- in second. Romney is third with 16.  (In Texas, there’s a robo poll -- a methodology NBC doesn’t report on -- that shows Santorum up 30. Should there be more evidence that shows similar results in live caller polls, we’ll report it.)

2. …But he’s also defending his own words
We’re not sure if the Philadelphia Daily News is one of Santorum’s morning reads, but if it is, he woke up to this headline from a Daily News columnist: “Santorum? Really? He's atop the GOP heap. Are they nuts?”

Depending on your perspective, Santorum either had a tough weekend or is standing up for very conservative values.

Yesterday on the Sunday shows and again today, Santorum was left defending remarks accusing President Obama’s of believing a “phony theology” that is not based on “the Bible;” pre-natal testing leading to abortions; the greatest generation during World War Two and how they stepped up – albeit late because they thought Hitler might not be that bad and then pivoted and said people “today” need to step up. That left some to wonder if he were likening Hitler to President Obama (More on the full remarks here); And there were his remarks on public schools, in which Santorum, who homeschools his children, said, “Where did they come up with public education was the role of the government? … The idea that state governments or the federal government should run schools is anachronistic.”

On almost all of those except pre-natal testing, which he defended, he tried to walk back or try to blame the media for overhyping them.

On “theology,” he said he wasn’t questioning Obama’s faith, that if he says he’s Christian, he believes him. And he changed his language today from theology to “ideology.” (Though a surrogate today also explained that there’s a certain “secularist theology” or “theological secularism” that Obama and liberals ascribe to.

On his World War Two comments, he said, “No, of course not,” he wasn’t comparing President Obama to Hitler. And: "It’s a World War Two metaphor. It's one I've used 100 times."

On education, on CBS’s Face the Nation yesterday, Santorum put it this way: “To the extent possible, with respect to mandates and designing curriculum and the like, I’d get the state government out. I think that the parent should be in charge, working with the local school district to try to design an educational environment for each child that optimizes their potential. … It’s another thing to dictate and micromanage and create a one-size-fits-all education system in states and certainly in the federal government, which is what President Obama’s trying to do.”

Not helping his cause today, spokeswoman Alice Stewart slipped and called Obama’s policies “radical Islamic policies,” instead of what she meant and said on the show as well – “radical environmentalist policies.” It’s a comment the left has had a field day with.

For those who have seen Santorum in person, he tends to go without notes, can speak for a long time, and meander into territory that, if there were a script, would be off of it. Now, these comments could actually help Santorum with very conservative voters. But they could hurt him not just with independents in a general election, but also with Republicans for whom electability matters most.

3. Romney Ariz. co-chair quits campaign
A co-chairman of Romney’s Arizona campaign Paul Babeu, who was seen walking along the border in that famous McCain “complete the dang fence” ad and is running for Congress, quit the Romney campaign after a report in the Phoenix Times alleged that he threatened to deport an ex-boyfriend if he didn’t keep quiet about their relationship.

He denies that accusation, but did come out at a press conference acknowledging he is gay. (MSNBC’s Thomas Roberts interviewed a reporter from the Arizona Republic who has been covering the story.)

4. Romney camp asks Trump to do radio
NBC’s Garrett Haake reported that, at the request of the Romney campaign, Donald Trump is now doing radio interviews for Romney in Ohio and Michigan. In one interview today in Michigan, Trump left open a third-party bid if Romney doesn’t win the nomination.

“There's a good possibility would do something,” he said, “because I love the country.”

He said Santorum “has no chance,” and that people in Pennsylvania turned him away. Locally, where they knew him best, was even worse.”

He said he went with Romney because of electability. Santorum, he said, “can’t win in a general. I see that and I see some of his views which are so out there, he cannot win the general.

He also acknowledged though one of Romney’s weaknesses – connecting with average voters. “He’s a much different guy on a personal basis than on TV,” Trump said.

And he also revealed that he knows Gingrich, because he is apparently a member at his D.C.-area country club.

5. Study: 50% of GOP ads negative
If you thought the ad wars this year were even more negative than ever before, you are right.

A new study by ad tracker CMAG/KANTAR media shows that just 6% of campaign ads in 2008 were negative in the GOP primary. This year, that number has jumped to 50 percent.

And you have Super PACs to thank for that. They have run more ads than the candidates themselves. And the Super PACs have spent about three-quarters of their cash on negative ads.

And, get this, 100% of Restore Our Future’s and American Crossroads’ ads have been negative.