Poll: Trump up 8 points in Iowa
© Getty Images

Donald TrumpDonald John TrumpPoll: Both parties need to do more on drug prices Senate approves .3 trillion spending bill, sending to Trump White House: Trump will delay steel tariffs for EU, six countries MORE opened up an 8-point lead over Hillary ClintonHillary Diane Rodham ClintonWhite House would like to see Biden ‘in the boxing ring’ in 2020 House Judiciary chair subpoenas DOJ for FBI documents The suit to make Electoral College more ‘fair’ could make it worse MORE in Iowa, a new poll finds.

Trump has 45 percent support to Clinton's 37 percent, according to a new Monmouth University survey released Thursday. Libertarian nominee Gary JohnsonGary Earl JohnsonWithout ranked voting, Pennsylvania's slim margins hide voters' preferences If weed is no longer a crime, why are people still behind bars? Gary Johnson: Trump admin marijuana policy shift could cost him reelection 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 GrassleyCharles (Chuck) Ernest GrassleyGrassley on Trump calling Putin: 'I wouldn't have a conversation with a criminal' Lawmakers zero in on Zuckerberg GOP senator blocking Trump's Intel nominee 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.