A surprise for many reasons. One: He’s not that old. He’ll be 72 on Election Day next fall, which means he’d conceivably have another two Senate terms left in him. Two: He represents a red state, Missouri, and would have been on the ballot during a midterm election that’s expected to favor the GOP. Three: He’s a McConnell ally and a member of the caucus leadership. If Cocaine Mitch ends up stepping down sometime before his current term expires, Blunt would have been an option to replace him as minority leader and potentially majority leader. Four: Although an establishmentarian with many years in Washington, Blunt hasn’t done anything conspicuous to earn the wrath of MAGA. He didn’t deliver any harsh anti-Trump speeches like McConnell did after the impeachment vote and he wasn’t vocal about opposing the effort to block Congress’s certification of Biden’s victory like John Thune was.

He likely would have been reelected easily, with little muss or fuss from the base via a primary, and then enjoyed a position of unusual influence within the caucus.

Instead he’s done. Why?

Blunt joined the Senate in 2010 after serving in the House for 14 years, six of which he spent in leadership as the Republican Whip.

Blunt’s decision to leave Congress after more than two decades come on the heels of Sens. Richard Shelby of Alabama, Rob Portman of Ohio, Pat Toomey of Pennsylvania and Richard Burr of North Carolina all announcing their retirements.

The 71-year-old lawmaker did not say explicitly why he was leaving after his term is up next year.

That’s five seats the GOP will have to defend next year without the advantage of incumbency, with two more in the pipeline depending upon what Chuck Grassley (who’s 87) and Ron Johnson (who’s leaning against running again) decide to do. Typically you don’t see a rash of retirements in a party that’s expected to reclaim a Senate majority in the next election, particularly involving a state like Missouri that’s a gimme for the GOP. Shelby’s retiring due to age (86) and Toomey, Burr, and even Portman could have faced tough-ish races in either the primary or the general election, but Blunt likely would have coasted. Especially with Trump and his supporters focused on punishing pro-impeachment Republicans next year instead.

Mitch McConnell must be in agony this morning. The GOP will hold the Missouri seat without difficulty but with Blunt out it’s a cinch that the primary will end up mirroring what’s happening in Ohio, with candidates like Jane Timken and Josh Mandel competing to one-up each other on who the Trumpiest option in the race is. Timken raised the bidding last week by calling on GOP Rep. Anthony Gonzalez to resign over his vote in January to impeach. That was a naked attempt to out-pander the rest of the field and hopefully cinch Trump’s endorsement, which would make her a prohibitive favorite in the primary. The same dynamic can be expected in Missouri now thanks to Blunt’s retirement. Which means McConnell’s caucus is destined to get Trumpier in 2023 even if it expands.

That may = explain why Blunt decided to throw in the towel. In late January he told CNN that he planned to run but hadn’t made up his mind yet. Possibly he was keeping his powder dry after the election to see how the party would react to Trump’s departure. If it seemed to Blunt like Republicans were prepared to move past Trumpism, he may have hung around. Once he realized that the GOP wasn’t going “back to normal” and that its congressional representation will only get more MAGA going forward, he may have concluded that not even the prospect of holding the majority was sweet enough to warrant “populists vs. establishmentarians” headaches for another six years.

I wonder if he’s been keeping an eye on how the junior senator from his home state has been faring lately. Josh Hawley was hit by a tidal wave of criticism for ringleading the effort in the Senate to try to block Biden’s certification in January, but he’s doing just fine with his target audience:

Sen. Josh Hawley’s effort to block certification of the 2020 election has been a fundraising boon — not just for him but his party, Axios has learned…

Digital fundraising appeals sent by the National Republican Senatorial Committee under Hawley’s name raised more money in February than those of any other senator except NRSC Chairman Rick Scott…

Hawley’s personal fundraising also has spiked, according to data provided by a source close to his campaign.

From Jan. 1 through March 5, Hawley’s campaign brought in more than $1.5 million from nearly 28,000 donors, the vast majority of whom had never given to him before.

It’s speculation, but I’d guess that Blunt decided that a party in which Hawleyism is ascendant and primaries are a pure competition for Trump’s favor isn’t worth another six years of devotion to a traditionally conservative septuagenarian.

Here’s his announcement. We’ll see what sort of figures step up to replace him. Democrats would love to have hardcore MAGA types like Marjorie Taylor Greene jump into primaries in states like Missouri and Ohio, not because they think those seats will be competitive for liberals but because they can exploit kooky GOP candidates in national messaging to try to win truly competitive seats elsewhere. I’m sure McConnell would prefer a Timken-like figure in Missouri, someone who’s posturing as an ardent Trumpist but who had solid establishment credentials in the Before Times.

Thank you, Missourians, for the opportunity to work for you and a better future for our state and our country. pic.twitter.com/1GjX74zhZB

— Senator Roy Blunt (@RoyBlunt) March 8, 2021