Democrats are hoping they can pull off one more special election stunner next Tuesday — and further panic House Republicans as they head into the home stretch of the 2018 midterm elections.

Franklin County Recorder Danny O’Connor (D) has closed hard on Ohio state Sen. Troy Balderson (R), pulling into a virtual tie in recent polling in a Republican-leaning district centered in the suburbs of Columbus, Ohio.

The race is the latest special election in a district that’s proven much more competitive for Democrats than it would have been in previous years, and the final beta test for the parties to work out their messaging before November’s crucial midterm elections. President Trump carried the district by 11 percentage points, other Republicans have won it by even wider margins, and it’s long been held by establishment-minded Republicans: Former Rep. Pat Tiberi (R-OH) held the seat for years, and an earlier version of the district was long held by now-Gov. John Kasich (R).

But in the Trump era, seats like this are in play. The district stretches from the edge of Columbus out through rural territory to Zanesville and other parts of central Ohio, and is the highest educated and wealthiest in the state. If O’Connor wins there next Tuesday, it’s the latest sign of a fierce suburban backlash against the president and his party — one that could very well hand Democrats control of the House next year. And even if he falls just short, that’s not a good sign for Republicans heading into November.

“The fact that it’s a close election sends the message: In a solidly Republican district, there are obviously a lot of people that are second-guessing the vision of the current Trump Republican Party,” former Ohio Democratic Party Chairman David Leland told TPM.

Both O’Connor and Balderson have proven themselves to be solid if unremarkable candidates — and that’s a big reason why Republicans privately concede a loss in this seat would be more worrisome for them than other special election results. The race essentially pits a generic Democrat against a generic Republican, as the pair of men have the pluses and minuses of political experience, with little to stand out from the average candidate.

“Both have run pretty vanilla, basic campaigns, no major mistakes and no extraordinary strengths,” one GOP strategist with deep Ohio ties told TPM. “The fact that this race is competitive with two candidates who are basically unknown tells you all you need to know.”

It’s not like the last big House special election Democrats won, where now-Rep. Conor Lamb’s (D-PA) military experience and near-perfect campaign combined with Republican Rick Saccone’s antagonism towards unions and lackluster efforts created a unusually good situation for Democrats.

The Republicans in charge of this year’s campaign are playing a home game as well: National Republican Congressional Committee Chairman Steve Stivers’ (R-OH) district isn’t far away, and Corry Bliss, the head of the Congressional Leadership Fund, managed Sen. Rob Portman’s (R-OH) blowout reelection victory in 2016.

“Them losing to Danny O’Connor should terrify them a lot more than losing to Conor Lamb,” said one House Democratic strategist.

Public and private polling of the race released in recent days has found a dead heat, though Balderson has held a lead within the margin of error in most surveys. The latest public numbers come from Monmouth University, which on Wednesday released a poll showing Balderson clinging to a narrow 44 to 43 percent lead among potential voters, with O’Connor edging into a one-point lead if the electorate ends up mirroring other special election models where Democrats have turned out in higher numbers.

“We feel great. We don’t need a poll to tell us we have momentum and enthusiasm on the ground,” O’Connor told TPM in a Wednesday phone call.

Republicans privately admit that O’Connor has had the momentum in the race, and they’re worried that in a low-turnout special election squarely in the middle of summer vacation season Democrats will have a huge enthusiasm advantage. That’s why they’ve dispatched Vice President Mike Pence to the district twice, with President Trump on the way Saturday to try to gin up enthusiasm on the other side. Early numbers suggest Democrats are requesting mail ballots at a much higher clip than Republicans, potentially enough to offset the district’s strong GOP tilt. Whoever wins, the candidates will face off again this November.

But while Republicans are nervous, most still think they’ll grind out a win — and believe a few things have gone their way in the race’s closing days.

First, after promising all campaign that he wouldn’t support House Minority Leader Nancy Pelosi (D-CA) for speaker, O’Connor said on MSNBC that if she wins the Democratic nomination within the party he’d vote for her over the GOP’s choice on the House floor. That undercuts the message he’s been pushing all campaign, one that’s in his final ad: That he’s a reasonable centrist who wants a change in both chambers of House leadership.

Second, after holding out for months, Kasich finally endorsed Balderson — and cut an ad for the CLF that’s running heavily on TV in the race’s closing days. Kasich, a frequent Trump critic popular with moderate Republicans and Democrats alike in the state, could help Balderson bring home wavering Republicans.

“Balderson’s up. Not by a lot, it’s close, but he’s up,” said one national GOP strategist. “The Pelosi comment certainly hurt O’Conner. That’s helpful. This Kasich endorsement, and the ad, will be very helpful over the next few days.”

Strategists credit both men for doing the blocking and tackling needed to put themselves in a position to win, though the Democratic base’s hair-on-fire excitement about this year’s elections have given O’Connor a leg up in fundraising.

That’s forced GOP outside groups to spend much more on the airwaves to match O’Connor’s larger TV buys.

But one source told TPM that O’Connor took a vacation to Greece with his fiance right after winning the May primary, two valuable weeks off the campaign trail during a shortened campaign season.

O’Connor confirmed the trip: “We decided on that one a long time ago, we got engaged in March and it was preexisting. She comes first and foremost in my life. That’s that.”

O’Connor brushed off the Kasich endorsement — “The sun rises in the east, sets in the west. The Republican endorsed the Republican” — and countered that Balderson has his own problems, like his comments that he’d support increasing the retirement age on Social Security and Medicare.

Balderson’s campaign didn’t respond to a request for comment for this story.