If Joe Manchin loses in West Virginia, that will be one mountain-mama of a story. RealClearPolitics now assesses the race as a toss-up, moving it out of the Leans Democrat yesterday as part of its Election Eve final calls. That would be perhaps the most stunning upset of the night, not because of West Virginia’s voting character but because of Manchin’s storied record as a political survivor:

Democratic incumbent senator Joe Manchin of West Virginia is in the fight of his political life, as his race against Republican Patrick Morrisey was changed to “toss up” on the eve of the election.

Manchin added a dozen events leading up to Tuesday, making stops across the state from Beckley to Marlinton to Bridgeport, before concluding with a “Take Me Home” motorcycle ride at his campaign headquarters in Charleston.

RealClearPolitics changed the Senate race on Monday from “lean Democratic” to “toss up” in response to gains made by Morrisey in the polls. Manchin now has just a 5-point advantage over Morrisey going into Election Day, according to the website’s average.

It’s not quite clear what moved the needle for RCP. The Free Beacon’s Elizabeth Harrington notes a poll commissioned by the NRSC that put Morrisey (no relation) up two points, which was reported two weeks ago. That was essentially an internal poll, though, and it’s not included in RCP’s aggregation of the West Virginia Senate race.

The RCP average gap in this race has gotten a lot a lot narrower of late. It’s still not within-the-MoE narrow, though:

RCP only lists three polls from October, which had Manchin up five, up five, and up sixteen. The latter, a poll from WSAZ, took place immediately following Manchin’s vote on Brett Kavanaugh, in which the Kavanaugh effect apparently lifted him from a +8 in the previous WSAZ poll. That’s the most recent poll in that series, so it’s impossible to know whether that got deflated or whether it was an outlier in the first place.

Best guess for why RCP moved it to toss-up is the status of the blue line more than the red line. Notice that Manchin never hit 50% in RCP’s average. He’s only been at 50% in one poll since July, that WSAZ poll from three weeks ago. An incumbent like Manchin running consistently below the 50% mark after decades in state politics is usually in serious trouble. And that looks to be the case tonight.