Late last night, Molly Ball explained what just went down in Mississippi:

Given the choice between an out-of-touch incumbent and a flawed challenger, Mississippi Republicans could not make up their collective mind. In a stunning result here Tuesday, the Republican civil war was fought to a draw. Senator Thad Cochran, a 41-year incumbent, took 48.8 percent of the vote, while state Senator Chris McDaniel, his Tea Party-aligned opponent, took 49.6 percent with more than 97 percent of precincts reporting late Tuesday. (One county had not reported its results because the election commissioner had gone to bed.) With the outstanding results unlikely to push either candidate over 50 percent, the two candidates appear headed for a runoff in three weeks’ time.

Beutler thinks the run-off won’t matter “in as much as McDaniel will be a junior Senator, who won’t vote much, if at all differently than Cochran would have”:

But it matters quite a bit as a reflection of the American right, and as a check against the growing narrative that Republicans have sloughed off their “Tea Party” problem. I’ve written skeptically of the idea that the GOP’s victories over “Tea Party” candidates this primary season are particularly meaningful. If the trick to beating “Tea Party” candidates is to nominate better-polished hardliners and throw tons of money at them, then the “Tea Party” hasn’t been beaten so much as the revanchist faction of the American right has been subsumed into the Republican party.

Weigel finds “no modern example of an incumbent senator losing the first round of a primary and winning a runoff”:

Cochran can’t bring any more Democrats into the electorate in three weeks, because Mississippi law prevents you from voting in one party’s primary and other party’s runoff.

So the Tea Party is war-whooping. FreedomWorks, which has been struggling after staff departures and weak fundraising, dispatched its president to the McDaniel victory party and sent reporters evidence of its hard work – 100,000 door knocks, 100 events, 40,000 yard signs. (You really can see the bold RETIRE COCHRAN songs all over the state.) The Tea Party Patriots Citizens Fund, a PAC that spent a half a million dollars on late ads, is currently meeting to discuss further investments.

Kilgore also doesn’t like Cochran’s chances:

[N]ow a deeply wounded Cochran faces a three-week runoff campaign in which many factors — especially turnout — favor his opponent. And with the heavy investment of groups like the Senate Conservatives Fund and the Club for Growth in Mississippi as their best prospect for a Senate RINO “scalp,” it would take a phenomenal effort by the incumbent or a big gaffe by the challenger to change the momentum in this race. When the smoke clears on June 24, Mississippi will likely join Kentucky and Georgia as states where the loss of a Republican Senate seat in November is possible, and the dissipation of GOP resources better spent elsewhere is certain. Beyond that, Republican pols everywhere would know that not even four decades of genial service and effective money-grubbing for a very poor state, or the support of virtually everyone there ever elected to a position above dogcatcher, is enough to survive the ever-rightward tide of the conservative activist “base.”

Should McDaniel become the nominee, Albert R. Hunt suggests that Democrats could win in Mississippi:

Before the primary, national Republicans admitted they were nervous over a possible McDaniel upset. They particularly feared the “Akin effect,” whereby his views would force other Republicans to either embrace or repudiate McDaniel. Still, the general feeling was McDaniel likely would squeak through in such a heavily Republican state. Actually, with a huge African-American population, Mississippi is not as red, or Republican, as it its neighbors, Alabama, Arkansas and Tennessee. In these three states, Barack Obama got less than 40 percent of the vote in the last presidential election; he got 44 percent in Mississippi.

Chait views this is wishful thinking:

[T]he most favorable polling still shows Democrats losing the seat even if McDaniel wins the nomination. As Nate Cohnshows, a majority of Mississippi is comprised of white Evangelicals who vote almost unanimously Republican in every election no matter what. So the only real question at stake is whether Mississippi’s Republican senator is a boring partisan or an entertainingly crazy one.