(Bloomberg) — Joni Ernst, like most Republican senators running for re-election in 2020, would like to stay focused on the bread-and-butter issues that voters say they care about rather than political fire surrounding President Donald Trump.Many of her Iowa constituents seem to want to avoid the impeachment controversy consuming Washington, as well. At a town hall meeting in Templeton, most voters instead talked about bolstering corn-based ethanol, preventing mass shootings, and coping with Trump’s trade war with China.But Ernst, a target for Democrats looking to take control of the Senate, couldn’t entirely avoid the uproar over Trump’s entreaties to China and Ukraine to help investigate a political competitor.“Where is the line?” asked Amy Haskins, a self-described independent and stay-at-home mom from Manning, Iowa. “When are you guys going to say, Enough. And stand up and say, I’m not backing any of this.”It’s a situation that increasingly will confront many of the GOP senators running for re-election next year as Trump looks to them and their colleagues as a firewall against his removal from office if the Democratic House impeaches him.Numerous recent polls have shown a shift in public support in favor of an impeachment inquiry of Trump, and his own public remarks suggesting China and Ukraine investigate a Democratic rival, Joe Biden, have only sparked more questions about his presidency.At the same time, Biden and the other 18 Democrats running to challenge Trump in 2020 are criss-crossing early primary and caucus states, such as Iowa, and delivering a barrage of criticism of the president.Some of the most vulnerable Republican senators in 2020, such as Arizona’s Martha McSally, Colorado’s Cory Gardner and Susan Collins of Maine, have avoided bringing up the topic of Trump’s actions.Collins has declined to comment, citing her potential role as a juror in any impeachment trial.But GOP lawmakers running for re-election in solid Trump states, such as Senator John Cornyn of Texas, have aggressively defended the president.Ernst says she hasn’t seen real evidence of impeachable conduct by the president, though she separated herself from him a bit.“I can’t speak for him,” she responded when Haskins also asked what she thinks of Trump’s dismissive treatment of past U.S. allies and his embrace of dictators like North Korea’s Kim Jong Un. “I’ll just say that. I can’t speak for him.”Ernst is favored to win re-election, but her fate next fall could be closely tied to Trump’s. Iowa is a classic swing state in presidential races.While Barack Obama won Iowa in 2008 and 2012, Trump won it by 9 points in 2016. But even before Ukraine and the impeachment inquiry, the president’s popularity had taken a hit in in the Hawkeye State. His net approval rating has declined 18 percentage points there since he took office in January 2017, according to tracking polls by Morning Consult.The Ukraine allegations and the impeachment controversy could make that worse, said Kyle Kondik, managing editor of Larry Sabato’s Crystal Ball election forecast at the University of Virginia. That risks turning Ernst’s race more competitive, he said.“If Trump loses Iowa, she’s probably endangered by that,” he said.Over a two-week congressional break, Ernst is making her regular rounds of the state — Templeton was her 33rd town hall this year — providing a window on what’s on the mind of voters.Economic IssuesAs angry as Haskins and some other constituents might be, most are focused on other issues, especially those affecting their farm-state economy that’s struggling under trade uncertainty. And many say they are so tired of the partisan controversies during Trump’s presidency that they have stopped paying attention.“I was in tune with the news and what’s going on with Trump in the first two years, but it got to be a soap opera. So I just kind of shut it out,” said Tim West, an elementary school teacher in Sioux City who said he’s an independent.A member of Senate Majority Leader Mitch McConnell’s leadership team, Ernst backed Trump immediately after the release last week of a rough transcript of his July phone call with Zelenskiy. In a prepared statement on Sept. 25, she said House Democrats were “ determined to impeach” the president, adding that “I’ve looked at the transcript, I don’t see anything there.”Until Thursday’s town hall, she hasn’t otherwise publicly addressed the issue. She’s been tweeting about corn-based ethanol and ending wasteful spending. Her travels back home have included a meeting with agricultural equipment owners and a leadership summit for students at a Sioux City university.Troy Price, the chairman of the Iowa Democratic party, said voters will expect Ernst to take a stronger position.“People want to know that their leadership is representing them and making sure that people aren’t putting their party over the people of the state,” Price said.Democratic ChallengerIn the 2020 Senate race, the Democratic Senatorial Campaign Committee has endorsed Theresa Greenfield, a farmer and Des Moines real estate firm owner. Other Democratic candidates include Eddie Mauro, who ran unsuccessfully for a U.S. House seat in 2018, and Kimberly Graham, a lawyer.A former Iowa state senator and Iraq War veteran, Ernst had a rapid rise in Iowa politics. Her convincing victory in the 2014 Senate race helped Republicans take a seat long held by Tom Harkin, a Democrat who had retired, and made her the first woman in Iowa to be elected to Congress.Trump considered her as his running mate before settling on Mike Pence, then the governor of Indiana.Ernst has largely stood by Trump since he took office, bBut she’s demonstrated an occasional independent streak. She has opposed his tariff policies, saying Iowa farmers were hurt after China retaliated with levies on some of the state’s key exports, including pork and soybeans. She also helped lead a GOP backlash over his plans to pull troops from Syria, pushed him to release his tax returns and chastised him for tweeting this year that four minority Democratic House congresswomen who are U.S. citizens should “go back” to where they came from.At a news conference on Thursday, Ernst said she didn’t see strong evidence of wrongdoing in the Ukraine-call transcript and a whistle-blowers report alleging attempts by Trump and other administration officials to compel an investigation of Biden and his son.“I am not concerned with what I have seen, given it’s face value, on the transcript or the whistle-blower complaint,” she said. But she added that the Senate Intelligence committee would investigate it in a bipartisan way, adding that “bottom line, we will get the information.”To contact the reporter on this story: Laura Litvan in Washington at firstname.lastname@example.orgTo contact the editors responsible for this story: Joe Sobczyk at email@example.com, John HarneyFor more articles like this, please visit us at bloomberg.com©2019 Bloomberg L.P.