Yes, I realize it’s Thursday, not Tuesday. What can I tell you? Tennessee goes its own way when scheduling primaries.

The bad news: Grassroots conservatives are staring at an ohfer this year in the Senate if Lamar Alexander beats Joe Carr tonight. The good news: Even though they haven’t unseated anyone, they’ve made lots of incumbents sweat. Dave Weigel posted a list today comparing the margins of victory in the primary for Senate Republicans targeted by righties with their margins of victory the last time they ran. Some, like Thad Cochran and Pat Roberts, were unopposed last time; others, like Mitch McConnell and Lindsey Graham, had token opposition. They all finished with a smaller share of the vote this year than they did previously. In fact…

If Alexander ends up short of 50% tonight, that'll be 3 senate GOP incumbents this year to earn less than 50% of the vote in primaries.

— (((Harry Enten))) (@ForecasterEnten) August 7, 2014

There are no more easy victories. Holding a seat nowadays means voting more conservative than you might like in the Senate and working hard on the trail to smother your challenger — and even then, as Mississippi proves, a runoff with lots of Democratic crossover votes might be necessary to rescue the incumbent. If Alexander wins tonight, take that as a comfort. The princes of the Senate no longer hold their seats as a matter of right.

Which brings us to Tennessee. What are the odds of Carr knocking off Alexander? Not great — the incumbent’s outspent the challenger five to one. Then again, Eric Cantor also outspent Dave Brat and got crushed thanks to an issue that’ll figure prominently in tonight’s race too, namely, immigration. Alexander was one of the 14 Republicans who voted for the Gang of Eight bill on comprehensive immigration reform last year. Carr’s been hammering him on that, as have Laura Ingraham (who campaigned for Brat against Cantor and campaigned recently for Carr) and the boss emeritus, who made the case against Alexander on Ingraham’s radio show earlier this week. There’s been almost no polling on the race so there’s no way to tell how close Carr is. The last one, taken more than a week ago, showed him within 12 points. According to Harry Enten of FiveThirtyEight, though, the tea leaves suggest that Alexander’s more ripe for an upset tonight that Pat Roberts was two days ago:

Republican incumbents also tend to do worse the more moderate they are, and Alexander is more moderate than Roberts. Per DW-Nominate’s first dimension, Alexander has the seventh most moderate record of any Republican senator in the 113th Congress. Although it’s on the more conservative end of defeated incumbents, Alexander’s score is within the range of other incumbent Republicans who have lost in primaries in the past decade…

Additionally, Republican incumbents tend to do worse when they’re seen as insiders, and Alexander is rated as more insider-y than Roberts. It was this measure on which Cantor looked most vulnerable. Per DW-Nominate’s second dimension, Alexander is ranked 12th among Republicans in the current Senate. Roberts comes in at 16th. Roberts’s score isn’t too far from Alexander’s, but it leaves Alexander in the more vulnerable position.

Finally, Republican incumbents have done better when they’re more firmly against immigration reform.

Alexander’s grade on immigration from NumbersUSA was a C+, the same as Thad Cochran, who barely survived his primary. And Cochran, for all his faults, voted no on the Gang of Eight bill. If amnesty’s going to take anyone down this cycle, it’s Alexander. (Er, right, Lindsey Graham?)

Tennessee is split between the eastern and central time zones so the polls close at different times. Part of the state will finish voting at 7 p.m. ET and the rest will finish at 8. You can follow results at RCP, Politico, or Ace’s Decision Desk. Here’s one of Alexander’s recent ads, in which he insists — no joke — that he voted against amnesty last year. He’s been arguing lately that what we have is de facto amnesty right now, ergo, voting for a terrible comprehensive bill that would have given illegals probationary legalization with no guarantees of better border enforcement was somehow a vote against amnesty. That’s how honest this guy is.