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Sen. Joe Manchin (D-W.Va.) announced on Thursday he isnt running for reelection, and I dont imagine there are many progressives shedding tears about it.

Manchin is the most conservative Democrat in the Senate by most reckonings, and its not an especially close call. Hes been giving grief to party leaders and undermining liberal causes ever since he first ran for that office, way back in 2010.

Manchin was West Virginias governor at that time, and Democrats had spent much of the previous two years trying to pass a bill that would limit carbon emissions through whats known as a cap and trade system. The Democrats didnt succeed, because Senate leaders couldnt round up the votes they needed to pass legislation that had gotten through the House.

West Virginia is famous for its coal industry, and Manchin wanted voters to know they could count on him to keep blocking such measures if they put him in the Senate. He also wanted to assure them of his strong feelings on the Second Amendment, which is a pretty big deal to those voters too.

His solution: a television ad in which he pulled out a shotgun and fired a bullet through a stack of papers that said Cap and Trade Bill.

Manchin won that race. And in the 13 years since, hes gone against progressives and party leaders just as frequently as he promised he would. That includes the time in 2021 he more or less single-handedly killed what President Joe Biden and Democratic leaders had been calling the Build Back Better bill.

The multitrillion-dollar package promised to reduce child poverty, to revolutionize caregiving, to bring down health care costs and to launch a transition to clean energy. Biden and Senate Majority Leader Chuck Schumer (D-N.Y.) had painstakingly negotiated with Manchin, over the course of months, and believed they were close to a deal only to have Manchin announce at the last minute that he was done and voting no, because the package was too expensive.

It was one of the most dismal days of Bidens tenure.

So Democratic leaders have plenty of reason to curse Manchin, as do the partys progressives. And if he runs a third-party presidential bid that takes votes away from Biden, as Manchin has hinted he might do , they will have even more reason to hate him.

But for now, at least, Biden and his allies should be thanking Manchin too because for all of the heartache, for all of the times he thwarted their plans, they almost surely would have accomplished far less over the past two years if he hadnt been around.

When it comes to Manchin, the single most important thing to remember is that he represents West Virginia, a state that has voted Republican in every single presidential election since 2000 and chose Donald Trump over Biden in 2020 by 39 points . It was Trumps second biggest margin of victory in the entire country.

Manchin has won statewide elections there because he talks, acts and votes more like a conservative. That record could reflect his deeply held values, or his determination to give constituents what they want, or some combination of the two. It doesnt really matter. It has kept him in office and for Democrats, thats a win, because the alternative to Manchin almost certainly wasnt a more progressive Democrat. It was a Republican.

Just think how differently the Biden presidency would have played out if, instead of Manchin, a Republican were in that seat from West Virginia. Even if it was a relatively moderate member of the party like Manchins West Virginia counterpart, Shelley Moore Capito, Republicans would have been in charge of the Senate in 2021 and 2022. They could have and almost surely would have blocked most of Bidens legislative agenda, and many of his appointments too.

Forget Build Back Better. There would have been no Inflation Reduction Act, either. And remember whats in that bill: substantial versions of two Build Back Better initiatives, the green energy investments and prescription drug price reductions , that Manchin ended up supporting.

Theres more. The American Rescue Plan, which provided critical relief during the pandemic and which Manchin also supported in the end, would likely have been smaller if Republicans had controlled the Senate back in 2021. And thats if it passed at all. The federal courts would look a lot different, too, because the Senate wouldnt have been confirming all of those Biden appointments over the past few years again, with Manchins vote.

And its not just major episodes of Bidens presidency that might have turned out differently.

During the Trump presidency, Manchin stood shoulder-to-shoulder with Democrats who opposed repeal of the Affordable Care Act. Had he wavered, it could have changed the political dynamics and, ultimately, made it possible for Republicans to pass legislation even with former Sen. John McCain famously voting no.

There are, of course, senators whom Democratic leaders and progressives have much better grounds for resenting. Arizonas Kyrsten Sinema (whos now an independent) comes quickly to mind, for her pivotal role killing some tax hikes on the wealthy and more aggressive drug pricing measures . Neither position was politically necessary for her survival. (Just ask her Arizona counterpart Mark Kelly, who won reelection after supporting both.)

Its a totally different story for Manchin. Democrats were lucky to have a Democrat in that seat for as long as they did. And if that wasnt clear before, it will be next year when as seems likely a Republican has replaced him.