Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE opened up an 8-point lead over Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE in Iowa, a new poll finds.

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Trump has 45 percent support to Clinton's 37 percent, according to a new Monmouth University survey released Thursday. Libertarian nominee Gary Johnson Gary Earl JohnsonWhat the numbers say about Trump's chances at reelection Presidential race tightens in Minnesota as Trump plows resources into state The Hill's Campaign Report: Biden condemns violence, blames Trump for fomenting it l Bitter Mass. primaries reach the end l Super PAC spending set to explode MORE had 8 percent, while Green nominee Jill Stein received 2 percent.

Trump led a July edition of the same poll by 2 points.

The GOP presidential nominee has improved among independent voters, leading Clinton, his Democratic rival, 44 percent to 29 percent.

But both are still plagued by negative favorability ratings.

“Iowa is one of the few places where Trump has been able make inroads among voting blocs that generally support Clinton,” said Patrick Murray, director of the Monmouth University Polling Institute.

Trump has been gaining ground in the polls both nationally and in several battleground states. Clinton now leads Trump by less than 2 points nationally, according to a RealClearPolitics polling average.

Thursday’s poll comes one day after Monmouth University released a poll in Nevada that showed Trump overtaking Clinton by 2 points.

The new poll also showed incumbent Sen. Chuck Grassley Charles (Chuck) Ernest GrassleyGardner signals support for taking up Supreme Court nominee this year Grassley, Ernst pledge to 'evaluate' Trump's Supreme Court nominee McConnell digs in on vow to fill Ginsburg's Supreme Court seat MORE (R-Iowa) up 17 points over his Democratic rival, former Lt. Gov. Patty Judge.

Grassley has 56 percent, with Judge at 39 percent.

Grassley has expanded his lead since July, when he led Judge by 10 points. His favorability rating has also improved, with 50 percent saying they view the GOP senator favorably, while 29 percent view him unfavorably. Judge has a positive favorability rating as well, but she’s relatively unknown; 52 percent have no opinion.

The poll was conducted from Sept. 12 to 14 and surveyed 404 likely voters in Iowa via phone. The margin of error was 4.9 percentage points.