North Carolinians will finally decide the last election of the 2018 midterms on Tuesday — and offer a glimpse of how Democrats might challenge President Trump in 2020.

The race is for North Carolina’s 9th congressional district, a conservative area that stretches east from Charlotte. Historically, it’s a safe district for Republicans. But Democrat Dan McCready fell just 905 votes short last fall — then watched the results get thrown out after a consultant working for his opponent was indicted for voter fraud. Now McCready, a Marine veteran and solar energy entrepreneur, is locked in a coin-flip race with North Carolina state Sen. Dan Bishop, who Republicans nominated to replace their 2018 candidate.

Republicans are doing everything they can to avoid an upset, including multiple visits by Vice President Mike Pence and a rally tonight with President Trump.

“This is by all accounts a fairly safe Republican district in a normal political environment,” said Michael Bitzer, a political science professor at Catawba College in North Carolina.

“We are not in a normal political environment.”

Trouble in the ‘burbs

The unusual dynamics are driven by Trump’s continued unpopularity among suburban voters, including in traditionally Republican areas like suburban Charlotte. That unpopularity is not only threatening Trump’s own reelection prospects but jeopardizing GOP House seats across the country. Republicans in those districts lost special elections last year, got wiped out in the November midterms, and are now enmeshed in a wave of retirements, as reality sets in that the GOP is unlikely to win back the House next year.

Still, losing North Carolina’s 9th district — which has been in GOP hands since the early 1960s — would be especially troubling. President Trump won the district by 12 points in 2016, a wider margin than all but three of the 42 House seats Democrats flipped in 2018. So a Republican loss would seem to signal a serious loss of Trump enthusiasm there.

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And “If that’s another seat that flips ... it could help spur another retirement or two,” said Doug Heye, a North Carolina native and longtime GOP strategist. “There's no doubt that they should be really concerned if they lose this seat — and still should be concerned if they win it [by a narrow margin].”

McCready’s allies say the tight race suggests that Trump is in trouble. The president carried North Carolina by less than four points in 2016. And if he’s losing North Carolina, he’s probably already lost the election.

“It sets up North Carolina to be a top-tier battleground in 2020, and that’s not something Republicans can feel good about,” said Morgan Jackson, a senior adviser to McCready as well as North Carolina Gov. Roy Cooper’s (D) 2020 reelection bid. “The suburbs are a big problem for him.”

Running on Trump

Bishop is a more establishment Republican than than their original nominee, a hard-right pastor named Mark Harris. But Bishop’s role in crafting the state’s controversial “bathroom bill,” which targeted transgender people, has caused him problems in the district’s more centrist suburban territory. And he’s not exactly running on moderation: He’s bear-hugging the president and looking to juice GOP turnout by focusing his ads in the district’s more rural media markets. His final ad of the campaign features Trump calling McCready a socialist and promising Bishop will be a “great congressman” who will “defend your values.”

McCready, by contrast, was one of the Democrats’ top recruits in 2018. His military and business background, as well as his moderate views, made it harder for Republicans to tar him as a lefty nut. He got a break during last year’s primary, when Harris defeated Rep. Robert Pittenger (R-N.C.). Harris appeared to have hung on for a close win last fall — until his consultant, McCrae Dowless, was charged with running an absentee voter fraud scheme. That led state election officials to toss the results and call for a new election, the first time in decades that’s happened.

Now McCready’s been running for Congress for two-plus years. He’s used strong fundraising and his own money to blanket the district in ads and build a strong field operation. And while Republicans believe enthusiasm for Trump has helped them close in on McCready in recent weeks, they’re worried that they’ve had to spend too much time and money to try to keep the district in their column in the first place. National GOP groups have spent more than $5 million combined to try to boost GOP turnout. Polls from both parties show a tied race.

A preview of 2020

If Democrats pull off the upset tomorrow, it would show the 2018 blue wave hasn’t crested. But McCready has succeeded by running to the center — something that could be harder to do if Democrats nominate a candidate from the party’s left wing, like Elizabeth Warren or Bernie Sanders, rather than frontrunner Joe Biden.

“Enthusiasm is on Democrats’ side,” said moderate Democratic strategist Kristen Hawn. “That said, heading into 2020 it depends a lot on who our candidate is.”

“We are not in a normal political environment.”

Republicans argue the electorate will look a lot different during a huge-turnout presidential election than on a sleepy Tuesday in early September. But they said the same thing about the special elections that presaged the 2018 midterms. And they admit that the tightness of this race is worrisome.

“You’re talking about areas that have been solidly red for more than 60 years, and they’re starting to shift Democrat,” Charlotte-based Republican consultant Larry Shaheen said about the district. “That’s concerning — more concerning than they’ve been treating it.”