But McConnell knew the challenge was coming and braced for it. Unlike his longtime colleague Richard Lugar of Indiana, who seemed not to realize his peril and the need to campaign seriously against Mourdock in 2012 until it was too late, McConnell prepared a war chest and fought back against Bevin. The senator may be unpopular—one GOP strategist told Politico Magazine last year, “No one likes McConnell. No Republicans even like McConnell”—but he's entrenched in Bluegrass State politics, and he cleverly moved to shore up his right flank, cozying up to junior colleague Rand Paul and hiring Jesse Benton, a former staffer to Paul and his father Ron, to run his reelection effort. Then he resorted to good, old-fashioned hardball politics, relentlessly attacking Bevin.

Not that Bevin helped himself. When Lee defeated Bob Bennett at the Utah Republican convention in 2010, he brought with him a sterling resume as a lawyer and former law clerk to Samuel Alito. Bevin, on the other hand, repeatedly got bogged down in damaging controversies that kept him from pressing his case against McConnell. It’s a good rule that when you're clarifying your view on cockfighting—more than once—you’re probably not in control of the direction of the campaign. (This really happened: Bevin attended a pro-cockfighting event, then claimed he hadn’t realized its purpose. Then he had to apologize when it emerged he'd answered a question about cockfighting, which he'd said ought to be a states'-rights issue.) Bevin sought to make McConnell's 2008 vote for the federal bailout program, known as the Troubled Asset Relief Program, a campaign issue, but it emerged that as president of an investment fund in 2008, he identified TARP as an economic bright spot.

As much as this race is about Kentucky-specific fundamentals, it's interesting to note the parallels with a couple of other vulnerable Republican senators, Mississippi’s Thad Cochran and Kansas’s Pat Roberts, whose challenges are still pending. Roberts has been battered over revelations of how little time he spends in Kansas these days, but his opponent, radiologist Milton Wolf, looks like a weak candidate, facing questions over macabre Facebook postings. Cochran’s opponent, Chris McDaniel, is this week engulfed in a controversy over images of Cochran’s ill wife, posted by a blogger with links to McDaniel. It seems possible that like Bevin, neither Wolf and McDaniel is strong enough to beat an incumbent.

As for McConnell, he’s not out of the woods. The Democratic nominee for Senate, current Secretary of State Alison Lundergan Grimes, has polled neck-and-neck with (and sometimes ahead of) McConnell. Democrats are extremely excited about Grimes: In an election year with a very difficult map and few pickup possibilities, their mouths water at the prospect of taking down the Senate minority leader and purging his procedural wiles from the chamber. But most prognosticators still rate McConnell a favorite against a fairly fresh candidate in a red state. But that's a worry for tomorrow: Tonight he can enjoy his commanding win.