There's a reason Trump and the Republicans are panicking, and his name is Danny O'Connor.

Democrat Danny O’Connor has taken the lead in the special election in Ohio’s 12th Congressional District — a seat that has been in Republican hands for most of the last hundred years.

Trump won Ohio’s 12th District by 11 points in 2016. The last Democrat to hold the seat was Bob Shamansky, who won a single term in 1980 before the district was redrawn to favor Republicans. Prior to that, the last Democrat to hold the seat lost it in 1938.

But O’Connor has been gaining support against Republican Troy Balderson — and for the first time, one major poll shows O’Connor in the lead.

A new Emerson College poll shows O’Connor just barely ahead of Balderson, 47 to 46 percent. But the poll has much worse news for Balderson — O’Connor leads with independent voters 56 to 28 percent over Balderson, and undecided voters are leaning toward O’Connor 61 to 17 percent.

O’Connor even has some support among people who voted for Trump. According to Emerson, just 3 percent of Clinton voters support Balderson — but 7 percent of Trump voters are switching sides to support O’Connor.

Balderson had been holding on to a razor-thin lead in the last few polls. So while this final poll of the district shows a boost for Danny O’Connor, things have been looking bad for the GOP in this solidly Republican district for a while now.

That’s probably why Trump took time away from vacationing at his New Jersey resort to campaign in Ohio this weekend, and attacked Danny O’Connor on Twitter, in a desperate attempt to salvage a district that shouldn’t even be close.

But the bumbling Trump also decided to attack Ohio icon Lebron James — and told his followers to vote for a candidate who isn’t even running in the August 7 special election.

Balderson has already been the beneficiary of campaign visits from national Republican heavyweights like Mike Pence and Paul Ryan, and has received a ton of cash from outside groups.

But O’Connor’s tremendous grassroots support has allowed him to overtake Balderson nonetheless.

The special election in Ohio’s 12th District will be the last major test for Democrats before the midterms. But the fact that the seat is even in play at all is already a defeat for Republicans.

If this last poll is any indication, though, the odds are better than ever that Danny O’Connor will be celebrating a victory on Tuesday night, and riding a blue wave to another victory in November.