Democrats are hoping Tuesday’s special election in North Carolina serves notice that their 2018 wins weren’t a fluke and that Republicans and President Trump should be worried going into 2020.

That this race is even competitive is noteworthy. It’s a suburban and rural North Carolina district stretching along the South Carolina border from Charlotte, and it’s traditionally Republican to its core. Trump won it by 12 percentage points. Republicans have represented it in Congress for a half-century. Now, Democrat Dan McCready is in a close race with Republican Dan Bishop for the open seat.

The election is happening nearly a year after all the other House elections because of an alleged election fraud scheme that benefited the Republican nominee in 2018 and which resulted in the election results being thrown out.

This is just one election for one House race. It’s also expected to be low turnout, given that it’s in an off-month in an off-year.

But what’s happening in North Carolina’s 9th Congressional District is not dissimilar to when Democrats won big, or got close, in special elections in 2017 in Trump country. Those strong performances precipitated Democrats winning back the majority in the House, which they did by winning 31 seats that Trump won. Now, they’re defending those seats, but their majority is such that Republicans will have to have a really good election next year to win back the majority.

Even Trump is acknowledging that this race could set the tone for the 2020 elections. In a sign of how nervous Republicans are about this seat, he traveled to the district Monday and held a rally, where he framed this as a test case for which party has the momentum going into 2020.

Vice President Pence also traveled there.

McCready doesn’t even have to win — if he comes within a percentage point or two here Tuesday, Democrats hope it will provide a road map to help them at all levels in 2020: They’ve campaigned by focusing less on Trump and social issues and more on health care.

North Carolina will be the center of the political universe next year. There’s a competitive Senate race, a competitive governor’s race, and it could be a battleground state for the presidential race.

North Carolina’s 9th Congressional District is made up of some key test constituencies for all those elections: suburban women (who were a swing vote in 2018), African American voters (whom Democrats need to turn out in high numbers for the presidential election) and rural voters (whom Trump needs). Democrats are using this district to try to test how to turn out black voters, since in 2016 they voted in lower numbers than in recent previous elections. They’re actually trying not to focus on Trump, or the alleged election fraud or the bathroom bill that tainted Republicans’ image in the state.

(It’s to be determined how much that worked. The Washington Post’s Mike DeBonis traveled to the district recently and found several voters who said they were casting their vote to support Trump or stick it to Trump. There’s also evidence that voters are thinking quite a bit about the alleged election fraud.)

Republicans argue this race is not indicative of where the national mood is. North Carolina Republicans have had a rough year. An operative working for the Republican nominee in 2018 is accused of forging mail-in ballots. Also, the state’s GOP chairman was indicted in April amid a campaign finance bribery scandal. And in 2016, Democrats won the governor’s mansion after national and local backlash to the Republican-led bathroom bill, which Bishop was the lead sponsor for.

“This phenomena will not be seen anywhere else and is one of the many reasons whatever the outcome is here, it’s a poor indication of national trends,” said a Republican strategist who spoke on the condition of anonymity to speak candidly about the race.

But with elections like these, perception matters almost as much as reality. So even if Tuesday’s election in this district is an isolated political event, DeBonis reports that Washington Republicans worry that their lawmakers could see a poor showing here as a sign that they won’t be able to win the House back in 2020, and even more could retire. (So far, 16 House Republicans have retired, opening up a path for Democrats to pick up seats in places like Texas.)

So yes, this is just one House seat in one state. But for many reasons, it’s a crucial state and, potentially, a crucial House race to signal what will happen in 2020.