The Democrats running for president, even those like Joe Biden and Pete Buttigieg who are being characterized as “moderates,” have some significant plans for legislation they’d like to pass if they become president. Doing so, however, would require their party to take back control of the Senate, where Republicans currently have a 53-to-47 majority. Such a victory won’t be easy, but it’s certainly possible, given that Republicans are defending more seats and have a number of vulnerable senators up for reelection.

But if you’re a liberal, what you may not have thought about — because it may be too depressing to contemplate — is what happens if Democrats win control by a vote or two, and the fate of the entire progressive project lies in the hands of Sen. Joe Manchin III of West Virginia.

We’ll get to the implications in a moment, but first, take a gander at this clip from an interview Manchin just gave to Fox News:

This was in reference to an interview Bernie Sanders gave in which he was asked whether Manchin and other more conservative Democrats would vote for his agenda, and Sanders said, “Damn right they will.” Not only is Manchin making clear he wouldn’t, but in answer to the question of whom he’ll vote for in 2020 if Sanders is his party’s nominee, Manchin said, “It wouldn’t be Bernie.”

This may not be all that surprising, given that by most measures, Manchin is the most conservative Democrat in the Senate. In fact, he’s just about the only Democrat who could win statewide in West Virginia, which Donald Trump won in 2016 by 42 points. Nevertheless, the appropriate thing for even a Democrat from West Virginia to say is not “It wouldn’t be Bernie” but “It wouldn’t be Trump.”

By the way, West Virginia is the poorest state in the country, so you could argue that Manchin’s constituents would benefit more than anyone else from Democratic agenda items such as universal health coverage, universal pre-K, enhanced workers’ rights and a higher minimum wage. How much is he really going to stand in the way of all that?

The answer is: probably quite a bit. Manchin’s entire political identity is built on being the guy who tells Democrats they’re being a bunch of dastardly libruls, and he has to pull the party to the right for its own good. Not only that, if he really holds the balance of power — if the Senate is 50-50, or if it’s 51-to-49 Democratic and he can join with another conservative Democrat (for instance, Sen. Kyrsten Sinema of Arizona, an unpredictable centrist who opposes getting rid of the filibuster), Manchin will have every incentive to throw sand in the gears of the party’s agenda.

That’s because if Manchin supports everything a President Sanders or a President Warren or a President Biden wants to do, he loses his power. He’d just be one vote out of 50 or so. If, on the other hand, he refuses to go along with health-care reform or whatever other bill is being debated, he immediately becomes the most powerful person in Congress. Democrats will have no choice but to give in and tailor their bills to Manchin’s liking if they don’t want the agenda to fail completely. And if he simply wants some part of that agenda to fail, he can make it happen.

Which may remind you of what happened in 2009 and early 2010, when Democrats had a filibuster-proof 60 votes in the Senate as they were trying to pass the Affordable Care Act. Without a single vote to spare, they had to consent to what conservative Democrats wanted. Most importantly, that meant kowtowing to Joe Lieberman, who had been defeated in a primary by a more liberal candidate, then ran as an Independent and won. Though the vast majority of Democrats were in favor of a public option, Lieberman made clear that if it was included in the bill, he’d join the Republican filibuster and kill the entire thing. How about allowing those over 55 to buy in to Medicare, something he had supported in the past? Nope, Lieberman killed that, too.

Joe Manchin is likely to become the 2021 version of Joe Lieberman, and the more he’s criticized by the left for sabotaging the progressive agenda and being the GOP’s best friend, the better it will be for him politically.

Sanders’s plan to deal with that is to pressure centrists such as Manchin by convincing them that, “If I don’t support an agenda that works for working people, I’m going to have President Sanders coming to my state and rallying working-class people." That doesn’t sound like something Manchin would be particularly afraid of. Then again, I’m not sure if the other Democratic candidates have a plan at all. And, of course, they have more pressing things to think about right now. But this is something any Democratic president is going to have no choice but to deal with.

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