He’ll be remembered fondly by Democrats as the man who used procedural chicanery to shepherd Obama’s terrible nuclear deal with Iran through the Senate.

Anyway. Corker’s 65, has served just two terms, won his last race five years ago by 35 points, and comes from a reddening state where he’d have been a heavy favorite to win a third term. If he’s retiring now, it can only be because (a) he hates serving in a paralyzed Senate under a loose-cannon president or (b) he’s ripe for a primary challenge given his establishment pedigree and Roy Moore’s likely victory in Alabama tonight.

Little of both, maybe?

“When I ran for the Senate in 2006, I told people that I couldn’t imagine serving for more than two terms. Understandably, as we have gained influence, that decision has become more difficult. But I have always been drawn to the citizen legislator model, and while I realize it is not for everyone, I believe with the kind of service I provide, it is the right one for me,” Corker said in a statement.

The 65-year-old senator became the first senator to announce his retirement this cycle, even as octogenarians Orrin Hatch (R-Utah) and Dianne Feinstein (D-Calif.) mull reelection. But Corker has grown frustrated with the Senate’s gridlock and couldn’t bring himself to run, said a person familiar with the situation.

He also would likely have faced a tough primary challenge next year from the right, likely backed by Steve Bannon. The former White House strategist met on Monday night in Alabama with Mark Green, who was mulling jumping into the race to challenge Corker.

Some Democrats are breathing heavily at the news, seeing Tennessee as potentially their key to taking back the Senate in 2018. Until now they had a seemingly insuperable problem: Even if they pulled a straight flush by successfully defending all of their seats next fall, including the ones in red states, *and* knocking off the two vulnerable purple-state GOP incumbents, Jeff Flake and Dean Heller, that still only gets them to 50. They’d need to swing a major upset against a Republican incumbent in a red state to grab a majority. Corker’s retirement puts Tennessee in play — in theory — especially when you remember that he won his first term in a nailbiter in 2006, by just three points over Democrat Harold Ford.

The problem for Democrats is that Tennessee today isn’t the Tennessee that sent Corker to the Senate 11 years ago in what was otherwise a blockbuster midterm for the left.

That’s NYT elections guru Nate Cohn, who went on to wonder if Tennessee wasn’t actually a more difficult pick-up for Democrats at this point than Texas. Unless the GOP nominates a total crank in the primaries (always a possibility!), odds are this seat is staying red.

It’s now an unwritten rule of politics that every Republican Senate contest must have one contender who’s nationally famous for whatever weird reason, even if that contender’s undeclared. Roy Moore was famous for refusing to follow the law on gay marriage and the Ten Commandments and he’s on the brink of winning a Senate seat in Alabama. Kid Rock’s famous for being the Pimp of the Nation and would almost certainly win the Republican nomination if he jumped into Michigan Senate’s primary, although he probably won’t. How about Peyton Manning for Senate in Tennessee? He’s a Volunteers legend and temperamentally seems like he’d play nice with establishment Republicans. (He spoke at a retreat for Republican congressional leaders in Philly this past January, in fact.) With no political record to attack and tremendous popularity, he’d be hard for any Bannon-backed populist firebrand to tear down. His name’s been kicked around for awhile as a possible successor to Tennessee’s other senator, Lamar Alexander, but now here’s a seat opening up in 2018 via Corker. Manning supposedly wasn’t interested in running as of several months ago but there was no obvious opportunity at the time. Now there is. I bet McConnell’s thinking about it already.

As for the Dems, there’s always Clay “The First Amendment and Boobs” Travis, whose political incorrectness has earned him right-wing fans but who likes to remind people that he voted for Obama twice. And of course there’s good ol’ Al Gore, who served the state previously in the Senate and is still only 69 years old, just a bit older than Corker. He has universal name recognition, he has the support of both centrist Democrats and global warmists, annnnnd … he’d probably get spanked given how much more conservative the state is now than when it elected him 30 years ago. Why would he come out of retirement to be humiliated on his home turf? (For the second time. George W. Bush won Gore’s home state in 2000, remember, which is the only reason the outcome in Florida mattered in the first place.) Cross your fingers and hope for a Manning/Travis race because the Goracle’s not going to bite.