CLACKAMAS COUNTY — In a close contest that could determine control of the House of Representatives, a Republican incumbent and her Democratic challenger appear to be competing for an unlikely title: most centrist.

In Oregon’s 5th Congressional District, Republican Rep. Lori Chavez-DeRemer and state Rep. Janelle Bynum, her Democratic opponent, are both running as moderates, touting their bipartisan records and policymaking chops, while trying to cast each other as ineffective and extreme.

Their fight for middle ground will matter not just for the district, but also for the balance of power on Capitol Hill: If Democrats keep hold of all the seats they currently represent, they need to flip only four from Republicans to win back the House majority.

They hope this district — which President Joe Biden would have won by 8 percentage points in 2020 — will be one of them.

National Democrats and some Republican campaign strategists believe Chavez-DeRemer won this blue-leaning district with a large number of unaffiliated voters in 2022 in part because the Democratic nominee that year, Jamie McLeod-Skinner, was too far to the left. Bynum’s candidacy amounts to a test of that theory.

Minority Leader Hakeem Jeffries, D-New York, personally asked Bynum to run, and House Democrats’ campaign arm, the Democratic Congressional Campaign Committee, took the unusual step of backing her over McLeod-Skinner in this year’s primary.

The political arm of a group of 100 pragmatic House Democrats, the New Democrat Coalition Action Fund, also invested significantly to boost Bynum.

“We could not afford to lose that seat again,” said Rep. Marc Veasey, D-Texas, who serves as the fund’s finance chair.

Republicans believe Chavez-DeRemer can hold the seat by focusing on issues such as public safety and the economy. Both parties’ campaign arms and affiliated groups have poured a combined $12 million into fall advertising in the district, which stretches from the southeast Portland suburbs through a stretch of rural communities and on to Bend and Redmond in Central Oregon.

In most competitive districts across the country, voters are evenly split between Democrats, Republicans and independents. In this district, the largest bloc of registered voters are those who describe themselves as nonaffiliated. Communities here have historically backed moderate candidates regardless of the party identifier next to their name, even though the state reliably elects Democrats for president and Senate.

Chavez-DeRemer, who served as Happy Valley mayor in a politically neutral capacity for eight years, has spent the past two years working hard to convince constituents that she is willing to work across the aisle. She often touts her record of co-sponsoring bipartisan bills, including several with Democrats from the Oregon delegation, to set better education, labor and drug abuse standards. She also notes that a bill she co-sponsored that would impose sanctions on criminals who trade fentanyl was signed into law.

“My message to the undecided is we’ve done the hard work,” she said in an interview. “We’ve built the team; we’ve listened to the concerns. I’m here to say you can have a different opinion. You can tell me what that difference of opinion is; you might be of the opposite party, but let me tell your story on your behalf too.”

But Chavez-DeRemer’s incumbency also could cut against her.

Over the past two years, demands by far-right members of the GOP caucus often resulted in tough votes for moderate lawmakers such as Chavez-DeRemer, including one that would bar using federal funding to pay for a servicewoman’s abortion if she crossed state lines, which she supported.

Democrats have worked to tie Chavez-DeRemer to those sorts of policies. They have emphasized comments Chavez-DeRemer made in 2022 suggesting she would support a bill that would federally ban abortion once a fetal heartbeat is detected. The congresswoman has pushed back, noting that she has not signed on to the Life of Conception Act, recently pledging to vote against any such bills, and helped influence House GOP leaders not to put any restrictive bills on the House floor for a vote.

House GOP leaders, who must often balance competing demands by moderates and far-right Republicans, have played up her independent streak as they’ve worked to help her hang on to her seat and keep them in the majority.

“You are very independent in taking care of your people at home,” Majority Whip Tom Emmer, R-Minnesota, said ahead of a fundraiser for Chavez-DeRemer in West Linn, this month.

Bynum, knocking on doors in Clackamas County on an unseasonably warm October morning, met two women who said they were supporting the Democrat because their top issue was reproductive rights — even though access is already protected in the state. Another woman said she was turning out to vote against “anything that the far right is trying to push that is just so against the Constitution.”

Later that afternoon, several home-care workers gathered at a Service Employees International Union potluck in Portland said they have endorsed Bynum because she has reliably explained how state bills could help or hurt the union.

But Lorne Bulling, the political director for Ironworkers Local 29, is splitting his vote, in part because he believes that Bynum’s work in the state Legislature has not resulted in significant job growth.

Bynum said she is cognizant of split-ticket voters and is working to prevent them. But she is also hoping to win over Republicans, acknowledging that she will just “roll with it” if she represents the district under a second Trump administration.

“I’ve served a purple district for eight years now, and I have always had the opinion that everyone deserved to be represented,” Bynum said in an interview. “Doesn’t mean I always agree with every particular angle, but it’s important for me to be a good lawmaker and to listen.”

Bynum also must work to convince independents and moderate conservatives that a vote for Chavez-DeRemer amounts to a vote for Trump, whom Chavez-DeRemer endorsed once he became the Republican nominee.

Diane Klinkenberg, an 80-year-old registered Republican who knocked on doors for Bynum, said she believes Chavez-DeRemer’s Trump endorsement means that she will vote the party line, especially if he returns to the White House.

Asked whether there are many other Republicans who are willing to cross the aisle to vote against Chavez-DeRemer, Klinkenberg said she hadn’t met one yet. “I’m hoping,” she added.

Cristal DeJarnac, the SEIU local chapter’s vice president, has been knocking on doors for Bynum. DeJarnac said Bynum must work to win over Democrats who still believe McLeod-Skinner, their party’s 2022 nominee, would be better able to represent rural communities than Bynum and Chavez-DeRemer, who are from the Portland suburbs.

“I feel like the politicians that are running and want those votes, they need to play to them and not just play to the Portland metro area,” she said. “We all need a champion in Washington.”