Mitt Romney and Rick Santorum are in a virtual tie in Michigan, site of the Feb. 28 Republican presidential primary, according to a new NBC News/Marist poll.

Romney, the former Massachusetts governor who grew up in the Detroit area, had 37 percent. Santorum, the former U.S. senator from Pennsylvania, trailed with 35 percent. Texas Rep. Ron Paul had 13 percent, while former House Speaker Newt Gingrich had 8 percent.

The candidates debate tonight in Arizona, site of another Feb. 28 primary, starting at 8 P.M. EST. The NBC/Marist poll showed Romney with a wide lead in Arizona.

Michigan is considered a key battleground, since a home state loss would be an embarrassment for Romney.The poll found him benefitting from a perception he is the best GOP bet to beat President Barack Obama in the fall.

Marist found that 51 percent thought Romney had the best chance to win; only 24 percent thought Santorum had the best chance. And 52 percent of those polled said that characteristic was the most important factor in their vote.

The poll was conducted Feb. 19-20. 715 likely GOP voters were surveyed. Margin of error is plus or minus 3.7 percentage points.

Ohio Attorney General Mike DeWine switched his support Friday from Mitt Romney to Rick Santorum.

"To be elected President, you have to do more than tear down your opponents," DeWine said in an announcement on the steps of the Ohio Statehouse in Columbus.

"You have to give the American people a reason to vote for you -- a reason to hope -- a reason to believe that under your leadership, America will be better.  Rick Santorum has done that.  Sadly, Governor Romney has not."

DeWine served with Santorum, a former Pennsylvania senator, in the U.S.  Senate

Romney and his supporters bombared Florida with negative ads, hoping to defeat former House Speaker Newt Gingrich. The Romney campaign lately has been criticizing Santorum for his spending record. Santorum leads Romney in polls in Michigan, site of a crucial Feb. 28 presidential primary. Ohio voters go to the polls a week later.

Mitt Romney could be in for a rough night Tuesday, as polls suggest former Pennsylvania Sen. Rick Santorum has a chance to win the Minnesota caucuses.

Romney's camp put out a memo Tuesday morning that looks ahead, and perhaps tries to lessen the impact of the Tuesday result.

"It is difficult to see what (former Massachusetts) Governor Romney’s opponents can do to change the dynamics of the race in February," said political director Rich Beeson in the memo. "No delegates will be awarded on February 7 -- Colorado and Minnesota hold caucuses with nonbinding preference polls, and the Missouri primary is purely a beauty contest.

"Except for the Maine and Wyoming nonbinding caucuses running through February, the next contests are on February 28 in states where Governor Romney is strong. Arizona’s 29 delegates will be bound in a winner-take-all contest. Michigan, the state where Governor Romney grew up, binds 30 delegates"

Beeson then looked ahead to March, with optimism.

"The rules for the March states offer even less comfort to Governor Romney’s opponents. With so many states and territories voting, organization and resources are key. Ours is the only campaign to be active in all of these states, and we have the resources and organization to maximize delegate totals according to each state’s rules," he said.

Santorum, former House Speaker Newt Gingrich and Texas Rep. Ron Paul all see possibilities in March. Gingrich and Santorum eye southern states holding primaries and caucuses, where GOP voters tend to be more conservative. Paul is pushing hard in caucus states.

Beeson says he's unworried. "Governor Romney is the only candidate prepared to compete in simultaneous contests across the country," he said.

"Speaker Gingrich’s and Senator Santorum’s campaigns have resource challenges. The remaining February states may not be kind to them, and their hopes for a comeback in March may be very difficult and based on an incomplete understanding of the delegate selection rules."

Just in time for the rest of the caucuses and primaries, trading card manufacturer Upper Deck is releasing "World of Politics" trading cards featuring the presidential contenders: from still-in-the-running President Barack Obama, Mitt Romney, Newt Gingrich, Ron Paul and Rick Santorum to also-rans like Rick Perry and Herman Cain.

The California-based company says nine subjects will be featured in all: "With so much attention around the 2012 election, we thought it was only fitting to produce a set of cards that would help pay tribute to all the highs and lows of this presidential race by capturing the top candidates on cardboard," said Jason Masherah, Upper Deck's marketing veep. The cards will be released Feb. 21.

It's not Obama's first time on a trading card: the trading card company released a caricature of Obama after he won in 2008. 

Days after endorsing Newt Gingrich in the Florida primary, former GOP prez contender Herman Cain says he'll launch a $1 million money bomb to raise money for the former House Speaker, who has promised to repeal Obama's sweeping health care legislation.

In an e-mail, Cain repeats his charge that had he been diagnosed with colon and liver cancer when the Obama plan was enacted, he "would not have survived!

"The doctors needed to move quickly, and thank God they didn't have to cut through red tape to do it,' he says in an email, asking for contributions to Gingrich.

Politifact found his assertion "false" in September, noting "there there is no part of the health care law that allows a government bureaucrat to weigh in on an individual's course of treatment -- not Cain's nor anyone else's."

Younger voters have tended to be Mitt Romney's weakest age group, but he won more support Tuesday from voters under 30 than any of the Republican candidates.

The Center for Information & Research on Civic Learning & Engagement, which studies youth voting issues, found in a preliminary analysis that Romney topped Texas Rep. Ron Paul by 16 percentage points.

About 100,000 young Floridians voted in the Tuesday GOP primary. Romney got 41 percent. Paul had 25 percent, followed by former House Speaker Newt Gingrich, 21 percent, and former Pennsylvania Sen. Rick Santorum, 13 percent.

Newt Gingrich's last scheduled stop before awaiting returns in Orlando was to a polling place in Disney's planned community of Celebration.

He visited with a small crowd of residents on the manicured lawn outside the picture-perfect Heritage Hall. Ron Paul signs seemed to outnumber Gingrich signs, though a few were sporting Gingrich stickers. He told one woman, "I need your help."

Spokesman RC Hammond told reporters that Gingrich intends to keep competing, regardless of what happens tonight in Florida.

Newt Gingrich told a small but enthusiastic crowd at an airplane hangar at Tampa Jet Center that a recent poll has him tied with Mitt Romney at 35 -35 -- though most polls show him trailing by double digits. (Gingrich didn't mention the poll was actually conducted before last week's final debate)

He appeared at a canvernous airplane hangar in Tampa where his campaign had curtained off 2/3 of the hangar, but the crowd didn’t fill the remaining third. He took the stage nearly 2 hours late, but offered no explanation – ripping quickly into Romney and Obama.

He ripped Romney and Obama, before closing with an appeal for help on Tuesday: "We really need your help, we need you on FaceBook, we need you Twittering, if that’s what you do, we need you on email,"he said. "We need you calling people, and to show I’m old fashioned we need you talking face to face …"

Republican voters still aren't crazy about their potential presidential nominees, according to a new Pew Reserach Center poll.

52 percent of GOP and GOP-leaning registered voters said the field is fair or poor. 46 percent have positive views of the field.

The survey was conducted Jan. 26-29 among 1,006 adults, including 341 Republican and Republican-leaning registered voters.

A month ago, just before the Jan. 10 New Hampshire primary, 51 percent gave the field excellent or good ratings. 44 percent rated it fair or poor.

The poll also found that more voters thought President Barack Obama understood the problems of average Americans more than top Republican contenders Mitt Romney or Newt Gingrich. 55 percent said the president understood them very or fairly well.

But 39 percent thought Romney understood well, and 36 percent felt that way about Gingrich.

Mitt Romney's lead is 20 in a new Suffolk University/7NEWS (WSVN-Miami) poll of likely Republican voters in Tuesday's Florida primary.

The former Massachusetts governor had 47 percent, while former House Speaker Newt Gingrich had 27 percent. Former Pennsylvania Sen. Rick Santorum got 12 percent, while Texas Rep. Ron Paul had 9 percent.

“It is almost certain that Mitt Romney will top his 39 percent showing in New Hampshire,” said David Paleologos, director of the Suffolk University Political Research Center in Boston. “This poll also tells us that Romney could reverse and exceed Newt Gingrich’s percentage and margin in South Carolina – and do it in Gingrich’s backyard.”