The first-term lawmaker is the fourth Republican to seek the party's nod to challenge Sen. Amy Klobuchar.

The former Pennsylvania senator picked up nearly 45 percent of the vote in the state's GOP caucuses.

Just two weeks ago, a PPP survey showed Gingrich with a commanding 36 percent to 18 percent lead over his next closest rival, Romney. Santorum was in third with 17 percent and Paul in fourth with 13 percent.

Obama's approval rating is still at just 49 percent, with 45 percent disapproving the job he's done in the White House. Last May, his approval rating was 51 percent.

A survey released Wednesday shows Gingrich with a 36 percent to 18 percent lead over rival Mitt Romney.

Bachmann's popularity continues to wane in Wisconsin, too. At just 5 percent in now, the last PPP survey pegged her support at 20 percent.

While Bachmann's numbers in Iowa are marginally better than she's seen elsewhere, they're likely still seen as disappointing given the premium Team Bachmann has placed on its performance there.

A new poll puts Bachmann at the bottom of the field: The only candidates she bests in the survey are Gary Johnson and Rick Santorum.

A handful of recent polls show that while Texas Gov. Rick Perry's support is sliding, the movement has not been to the benefit of Minnesota's Michele Bachmann.

Michele Bachmann enjoys support from just 8 percent of likely GOP primary voters in the presidential contest, according to a new national poll by Rasmussen Reports. Texas Gov. Rick Perry is the top choice, garnering support from 28 percent of respondents, with former Massachusetts Gov. Mitt Romney close behind at 24 percent.