Mitt Romney's argument for why he'd be a better president than Barack Obama is that he'd be a better manager of the economy, but a new poll finds that a majority of Americans think at least one Obama economic policy worked. Here's our guide to today's polls and why they matter.

Findings: A majority, 56 percent, think the auto bailouts were "mostly good for the economy." In October 2009, 54 percent thought they were "mostly bad for the economy." But Americans' views on the bank bailout haven't changed at all -- 51 percent thought they were the "wrong thing" in February 2010, and 52 percent think they were wrong now. A plurality, though a smaller one, thinks Obama's 2009 stimulus was a bad idea.
Pollster: Pew Research Center
Methodology: Survey of 1,501 Americans from February 8 to February 12.
Why it matters: The Obama campaign released an ad in Michigan Thursday highlighting Obama's Detroit bailout, and noting that all the Republican candidates were against it. Romney's central argument is that Obama's economic policies made the recession "worse and longer." Those policies include the auto bailout that Romney opposed, a position he's working to defend in Michigan.
Caveat: People will care less about whether they feel like Detroit jobs were saved than whether their own jobs were saved.

Findings: Obama's ahead of Romney in Virginia, 49 percent to 43 percent.
Pollster: Rasmussen
Methodology: Robocalls to 500 likely voters in Virginia on February 21.
Why it matters: One of the ways the Obama campaign thinks it can get to 270 electoral votes is with the typically red southern states Virginia and North Carolina. That's looked unlikely because Romney polled ahead of him for months. "The question is whether this makes Bob McDonnell that much more of an attractive VP pick," The Hill's Christian Heinze writes. Rasmussen finds Obama beating Santorum 51 percent to 43 percent.
Caveat: Rasmussen leans right.

Findings: Santorum is doing better against Obama nationally, getting 48 percent to the president's 49 percent. Romney is ahead of Obama 50 percent to 46 percent.
Pollster: Gallup
Methodology: Tracking poll of 898 registered voters from February 16 to February 19.
Why it matters: It hurts Romney's "electability" argument. Santorum is gaining on Obama while Romney has been steady since September.
Caveat: Gallup says how the candidates perform in Tuesday's vote could change how they fare against Obama.

Findings: Santorum's ahead of Romney in Michigan 37 percent to 34 percent. 
Pollster: Detroit Free Press/ WXYZ-TV
Methodology: Survey of 400 likely Republican voters from February 17 to February 20.
Why it matters: This is Romney's home state. And 45 percent say they might change their minds before election day.
Caveat: The poll was taken before the final primary debate, so the candidates' performances weren't factored into voters' picks.