Don’t look now, but Democrats just flipped their 36th state legislative seat this cycle.

Tuesday’s win in Florida House District 72 was not only yet another Democratic win in a seat Trump carried in 2016 (by a 51-46 margin), but it was also a stark reminder for Republicans of how much trouble they may be in at the ballot box in November.

Democrat Margaret Good, an attorney and community activist, defeated Republican James Buchanan 52-45 percent, improving on the 2016 Democratic presidential performance in this Sarasota County-area district by 12 points. This historically Republican seat, which has a GOP voter registration advantage of around 13,000, became vacant upon the abrupt resignation of a freshman lawmaker in August 2017.

Buchanan is the son of Republican Rep. Vern Buchanan, who has represented the area in the U.S. House since 2007. Perhaps the elder Buchanan’s influence is what helped turn Republican attention to this otherwise under-the-radar state House race, or perhaps Republicans are just trying to fight the narrative of Democratic success arising from the apparently inexorable trend of the GOP losing seats in special elections. Whatever the reason, national-level Republicans shifted into high gear to save this seat in the contest’s final days.

A late poll had Rep.-elect Good pulling slightly ahead of Buchanan on the even of the election, 48-45 percent—a 6-point swing from a Jan. 24 poll that had Buchanan in the lead with 49-46 percent. This shift in polling came on the heels of a Trump-style Buchanan rally on Sunday that featured a guest appearance from former Trump campaign manager Corey Lewandowski and chants of “lock her up,” because that’s where Republicans still are, apparently.

Good also had a national-level campaign booster, in the form of former Vice President Joe Biden, who endorsed the Democrat about a week before the election and recorded a robocall for her campaign. Former Maryland Gov. Martin O’Malley headlined a fundraiser for Good, too.

Good outpaced her GOP opponent in fundraising in the final weeks of the race, bringing in about $484,000 to Buchanan’s $353,000. However, both sides were targets and beneficiaries of outside spending, so each party’s final investment in this contest will only get tallied in full at a later date. Good’s field program was robust and drew heavily on local grassroots energy: Volunteers reportedly made over 120,000 phone calls and knocked on 45,000 doors in the district. Good herself knocked on 2,000 of those.

Indeed, voter turnout in this race was record-setting. Going back 15 years, the biggest state House special election on record came in 2008, when total turnout was 22 percent. Before polls even opened on Tuesday, absentee and in-person early voting turnout was 3 percent. That number jumped to 25 percent by 11 AM ET the day of the actual election.

With Republicans losing so many seats in special elections over the course of the cycle, it could be easy to grow inured to the significance of these Democratic pickups. But Tuesday’s Florida win for Team Blue might be one of the most worrisome yet for GOP candidatesthis fall. This seat not only went for Trump, it had traditionally supported Republicans down-ballot as well. What’s more, Buchanan benefitted from his father’s name recognition and Republicans had a significant voter registration advantage in the district. To top it all off, national Republicans took interest, even sending a key Trump campaign operative to help get out the vote.

And Republicans still couldn’t keep this seat.

However worried the GOP might be about elections this fall, they’re not worried enough.