McConnell versus Bevin was supposed to be the big establishment/tea party war this year but McConnell turned it into a rout weeks before election day. Brat versus Cantor ended up being a rout for the tea party but that result caught everyone by surprise, including tea partiers. Tonight’s the first and last campaign of the season where both sides have gone all in — the 2008 GOP ticket is on opposite sides — and the outcome’s in doubt as voters go to the polls. If McDaniel wins, it’ll be just the third time a Republican incumbent’s been bounced in a primary since 2009. If Cochran wins, it’ll be … depressing.

If you need a quickie primer on this race, take three minutes to sift through last night’s Quotes of the Day. Senate Republicans have ante’d up for Cochran knowing that a loss makes it more likely that they’ll be primaried too. Most polls show McDaniel ahead, two of them by eight points or more, but (a) none of those polls was taken by a major nonpartisan pollster and (b) Cochran’s last-ditch strategy involves turning out Democrats, an X factor that wouldn’t show up in surveys of the GOP electorate in Mississippi. So long as you didn’t vote in the Democratic primary earlier this month, you’re eligible to vote in tonight’s GOP runoff — regardless of party registration. That’s why Cochran’s campaign, backed by the GOP establishment inside and outside of Mississippi, has doubled down on calling McDaniel an “extremist.” Most people thought they’d take it easy on McD in the runoff for fear of badly wounding a guy whom they’ll probably be stuck with as their nominee. Instead, Cochran went scorched-earth on him, hoping to convince Dems (especially black Democrats) that McDaniel represents racist tea partiers who’d surely choke off the federal spending that the state’s subsisted on for decades. Harry Enten:

Cochran has made a concerted effort to reach out to African-Americans, who make up 37 percent of Mississippi’s population, although usually less than 5 percent of Republican primary voters.

In most other states, Cochran’s effort might seem odd. Why would Democratic-leaning voters want to choose the Republican candidate who hasn’t won less than 60 percent of the vote in any of his five previous re-election campaigns? Because the chances of a Democratic victory in the fall are slim, no matter whom Republicans nominate. Mississippi’s electorate is inelastic. As I have previously noted, 80 percent of white voters in the state are likely to vote Republican. And because whites make up the majority of voters, Democrats have a narrow path to victory.

Cochran is hoping that black voters recognize this and show up at the polls. If they do, it will be most obvious in Holmes County (to the north of the capital city of Jackson) and Claiborne and Jefferson counties (which are to the southwest).

Obvious strategic dilemma for Dems: Would your nominee stand a real chance against McDaniel in the fall, or are you doomed to lose in a state this red and therefore are better off losing to Cochran? Some black pastors have settled on the latter view. The obvious strategic dilemma for Republicans is what happens to turnout in the fall after a race this nasty, especially if Cochran ends up winning on the strength of Democratic support. Would tea partiers stay home rather than vote for a nominee chosen by the other party? Would Cochran voters stay home if McDaniel ends up winning because they refuse to support an “extremist”? The Democratic nominee in Mississippi this year is an underdog but not a pushover. And an awful lot of money’s been spent making hard feelings in the losing camp tonight even harder.

Polls close in Mississippi at 8 p.m. ET. You can follow results at RCP, Politico, or my election site of choice, Ace’s Decision Desk. The only other major race tonight is in New York, where another congressional dinosaur’s resisting extinction caused by demographic shifts in his district. Rangel’s been in the House since 1971; he just turned 84 years old; there’s zero chance he’ll be back in the majority and chairing a committee in the near future. You would think he’d be ready for retirement, but lifers like him and Cochran cling to their seats out of pride and because influential friends don’t want to have their influence diminished, not because there’s any legislative work that they feel is unfinished. It’s grotesque, but that’s American democracy for you until we get our act together on term limits. The polls in New York close at 9 p.m. ET.

Update: Prediction:

Update: Hmmmm.

Update: Will it really be over tonight?

Update: Still very early at 9 p.m. ET, but the Decision Desk sees hope for the incumbent:

Also this:

Update: I thought the chances of Dems turning out in numbers for Cochran were low, but maybe not:

McDaniel’s strongest counties, including and especially Jones, haven’t come in yet so he’ll gain on Cochran soon. But by how much?

Update: A little good news for the challenger:

Update: It’s Cochran’s night — so far.

Update: Keep hope alive, McDaniel fans:

Update: Jones County will need to come up very big for McDaniel:

Update: Two-thirds of Jones County is now in. McDaniel leads big, but not big enough:

Update: Food for thought:

Update: The Decision Desk has seen enough:

Let’s see how long it takes MSM outlets to follow suit.

Update: Dave Wasserman of the Cook Political Report follows suit:

Update: Wow:

Update: Still a glimmer of hope for McD fans?

Update: Now Wasserman’s having second thoughts:

Update: Down to the wire:

Amazingly, turnout tonight has surpassed turnout in the first primary election three weeks ago. That’s how hot this race was.

Update: McDaniel’s close, but maybe not close enough:

Update: Running out of time…

Update: The AP throws in the towel:

Three cheers for earmarks!

Update: Double wow — Cochran’s Democratic strategy worked like a charm:

Does this mean red-state Dems like Landrieu and Pryor have a better shot than everyone thinks?