Susan Davis

USA TODAY

WASHINGTON — Republican Joni Ernst enjoys a narrow lead and an atmosphere favoring a GOP victory in the Iowa Senate race against Democratic Rep. Bruce Braley, according to the latest USA TODAY/Suffolk University poll.

Ernst leads Braley 47%-43% among likely Iowa voters, taking a narrow lead in a race where 7.4% of voters remain undecided in one of the handful of contests that will determine which party controls the Senate next year.

A late August USA TODAY/Suffolk University poll showed the race tied at 40%. Today's survey gives Ernst the momentum in the final three weeks of the campaign.

Other indicators in the survey also depict a favorable political atmosphere for Republicans.

President Obama has a 54% disapproval rating in the state that helped launch his 2008 presidential campaign to victory.

Ernst has a narrow edge in "favorability": 46% of respondents viewed her favorably compared with 43% for Braley.

Although enough voters remain undecided to swing the race in either direction, the poll also gives Republicans a 7.6-point advantage in the generic ballot. That is, when asked whether they would vote for the Republican or the Democratic candidate, 48.6% said Republican, 41% said Democratic. Ernst also has a 48%-32% edge among independents.

"There are three questions: Who is going to win the remaining undecideds? Who can whittle down the other's poor numbers? What will be the makeup of the actual vote?" said David Paleologos, director of the Suffolk University Political Research Center.

The remaining undecided voters are independents who have generally negative views of both candidates.

"These are people who pretty much hate everybody," said Paleologos. "It's a tough crowd."

Jason Lewis, 35, a respondent in the poll, said he remains undecided three weeks out. He has not ruled out voting for one of the third-party candidates on the ballot because he's not confident either Ernst or Braley would be an independent voice for Iowa in the Senate.

"I focus more on state issues. What, if anything, can that one person do to represent who they are representing?" he said. "I'm so afraid that even though they're trying to represent Iowa, they'll be forced either by money, by greed, by bullying" to toe the party line.

Braley's vote in favor of the Affordable Care Act earned him some support. Health care is the most important issue to Iowans, at 25%, followed by jobs at 17%. However, 52% of Iowans say the ACA has been "generally bad" for the state, and 38% say it has been "generally good."

"We've seen nothing but positive things about the new Affordable Care Act," said Jessi Williams, 36, a medical social worker, who said Braley's vote for the bill secured her vote. Ernst supports repealing the law, but she has not offered an alternative.

Like most Senate races this year, Iowa has been a personality-driven contest. A GOP attack against Braley for a dispute he had with neighbors over chickens that was settled out of court resulted in 18% of Iowans saying they'd be less likely to vote for him — but 72% said it makes no difference at all.

Democrats have attacked Ernst's support for proposing eliminating the Department of Education and the Environmental Protection Agency, and 40% of Iowans said her position makes them less likely to vote for her, while 41% said it makes no difference to their vote.

David Bunkofske, 69, is an Ernst supporter, citing her military service as particularly appealing. "She believes in the things I believe in: She believes in gun rights. She's against abortion, and she's military. It's mainly her stance on conservative views," Bunkofske said.