"I can’t outspend him. We can’t even match him. He raised more money in a quarter than I’ve ever raised in a year in my life. But we can outwork him," DeFazio told supporters on a virtual phone banking on Thursday, the same day that both candidates disclosed their latest fundraising haul.

Democrats say they’re particularly anxious because of DeFazio’s position in the party — an infrastructure maven who is primed to play a major role on one of Joe Biden’s biggest priorities if he wins the White House next year. He's also been a key player in Congress's stimulus funding stalemate, a strong proponent for airline relief who has even bucked Democratic leadership at times.

Party officials say they expect to hold the seat, and DeFazio retains the advantage with his enormous $2.12 million cash on hand, nearly a million more than his opponent. Still, senior Democrats have grown nervous and officials acknowledge the race will be closer than they'd like.

The 73-year-old House Transportation chair has handily won every contest in his sprawling southwestern Oregon district since he first ran for office three decades ago, even as it has tinted slightly redder over the years. But this marks the first time DeFazio has fielded a serious opponent in years.

“It’s a district that when Peter decides to retire or move on, will probably be the most competitive district in Oregon,” said Mark Wiener, a political strategist in Oregon who has not worked with the DeFazio campaign. “Skarlatos is a blank slate with a big checkbook and the Republican establishment is pretty desperate for a win in some place.”

“This is the kind of race where if you catch the incumbent napping, you can have an upset. Peter DeFazio doesn't take naps,” Wiener added.

DeFazio supporters say he has taken the challenge seriously, and that the House Democrats’ campaign arm, the Democratic Congressional Campaign Committee, has stepped up to protect him. But they also acknowledge certain wild cards in the race — including the wildfires ravaging northwestern Oregon and the absence of his usual voting base of college students.

Election forecasters have recently shifted his race from likely to lean Democrat, and while it still favors DeFazio, Skarlatos is now within striking distance.

The race is also on track to be the most expensive congressional race in Oregon's history.

Republicans have spent $1.5 million on ads, including a $350,000 buy in the final run-up to the election, according to the most recent data compiled by Ad Analytics.

But DeFazio and Democratic groups have spent more, a total of $2.65 million on ads, as of Thursday. That includes $800,000 in ads in the final days of voting.

"I have never taken any election for granted. We’re working hard. We have a great ground game," DeFazio said in a statement

DeFazio supporters say his populist-tinged progressivism appeals to voters in his purple district, which includes the state’s third-largest city, Eugene, as well as rural towns in timber country and up the Oregon coast.

The tight race is a far cry from DeFazio’s usual reelection: The 17-term congressman has faced the same GOP challenger — a proponent of “alt science" who collects urine samples for study — for five elections in a row. DeFazio has beat that opponent, Art Robinson, by double digits every cycle.

But this year is different for a host of reasons, including a celebrity GOP candidate who competed on "Dancing with the Stars," starred as himself in a Clint Eastwood-directed film and has become one of Republicans’ only hopes for a pick-up in a terrible year for the party.

DeFazio’s district has also suffered from historic wildfires, forcing thousands to flee. Before that, Eugene saw weeks of racial justice demonstrations — some of which morphed into rioting as Black Lives Matters supporters clashed with counterprotesters.

Another problem for Democrats: Thousands of students at the University of Oregon — who typically cast votes from Eugene — are learning remotely this fall amid the coronavirus pandemic.

Skarlatos has tried to put DeFazio on the defense, highlighting DeFazio’s support for the "Green New Deal," which one ad claims could “kill the timber industry.” Skarlatos has also falsely stated the Democratic chairman lives on a “yacht.” (DeFazio lives on a 32-foot houseboat, which he said he bought for $16,500.)

The ex-National Guardsman, dubbed a "hero" after stopping the train attack, has also accused DeFazio of wanting to defund the police — an issue that has been top of mind in Oregon and across America after a summer of months of protests in major cities.

“I do think people in Oregon are seeing it up and close and personal, unlike a lot of people in the country,” said Mike Leavitt, the lead consultant for the Skarlatos campaign, in an interview about the national policing reform debate. “I do think that is an issue that resonates with them.”

But Leavitt stressed that Skarlatos’ campaign is more than just one issue: “I think people are just interested in a new face, in new ideas."

"Congressman Defazio has been in Congress longer than Alek has been alive," Leavitt added.

Democratic groups have flooded the district in response, accusing Skarlatos of blindly backing Trump or wanting to dismantle health care protections.

In Washington, DeFazio allies say he has maintained his independent streak even after picking up a key gavel in 2019.

As chair of the Transportation Committee, DeFazio has been increasingly aggressive in recent weeks as he’s sought to deliver relief to out-of-work airline employees amid the pandemic and months of stalled negotiations over coronavirus relief measure. At times, that has meant bucking Speaker Nancy Pelosi on the issue of whether to pass standalone relief bills.

The Oregon Democrat has publicly and privately demanded a standalone bill to help prevent layoffs and to reverse around 40,000 furloughs which went into effect this month. Pelosi, meanwhile, has been adamant that Democrats will not pass a bill on the floor unless it includes expansive relief across the U.S. economy, and not just for airlines.

Still, DeFazio has come under intense pressure from labor groups to deliver the aid, and at one point the Oregon Democrat even tried to force a vote on the floor to extend the airline relief. Republicans, however, objected to the maneuver.

DeFazio is hardly the only Democratic incumbent to face a tough reelection this year, with prominent primary challenges to House Oversight Chair Carolyn Maloney (D-N.Y.) — a race that took weeks to count and certify — and 16-term incumbent House Foreign Affairs Chair Eliot Engel (D-N.Y.), who was ultimately defeated by his liberal challenger, Jamaal Bowman. House Agriculture Chair Collin Peterson is in a toss-up race to hold on to a rural Minnesota district that Trump won by 31 points in 2016.

“I expect both sides to keep fighting hard, but I’ve been very impressed by how seriously the DeFazio campaign is taking this,” said Carol Butler, another campaign veteran in Oregon.

“The district’s tough, and has gotten tougher over the years,” Butler added, but noted that DeFazio has remained popular, with a reputation of something of a maverick. “Any other Democrat, I’d be a lot more worried.”

Democrats say there could be huge repercussions for losing their party’s leading man on infrastructure just as a potential President Joe Biden enters the White House with his own broad plans for rebuilding the nation’s roads and bridges.

As the top Democrat on the Transportation Committee since 2014, DeFazio has already been in talks with Biden staffers and has pushed to be a major part of the administration’s infrastructure plans.

Some outside observers downplayed the impact of a DeFazio loss on infrastructure plans for a potential Biden White House. But if he does fall, Democrats would be forced to scramble to find a replacement with the expertise and influence of the Oregon Democrat.

Jim Burnley, a former Transportation secretary in the Reagan administration who still works on infrastructure issues and is close to DeFazio, said DeFazio himself has described the challenge as “very, very serious” and is working hard to keep the seat. If he does, Burnley said, it would be a boost for any potential infrastructure bill.

“If the Democrats retain the House, he's the sort of leader that you would want to see,” Burnley said.

Tanya Snyder contributed to this report.