What Kyrsten Sinema’s party switch means for John Fetterman and Senate Democrats

Well, that didn’t last long.

Democratic elation after John Fetterman came through on his pledge to become the party’s 51st Senate vote — a promise made whole when Sen. Raphael Warnock won reelection in Georgia Tuesday — ran into a speed bump Friday when Sen. Kyrsten Sinema, of Arizona, announced she’s leaving the Democratic Party and becoming an independent.

(Pennsylvania has seen this before: The last senator to change parties was Sen. Arlen Specter, who left the GOP to become a Democrat in 2009, only to be replaced by Sen. Pat Toomey, the Republican now being replaced by Fetterman).

On the surface, Sinema’s move might eat up some of the wiggle room Fetterman’s election was expected to provide Democrats, who have spent the past two years delicately navigating a 50-50 Senate. Fetterman pointed repeatedly to that dynamic, promising to be the extra vote his party often needed for its priorities when Sinema or Sen. Joe Manchin (D., W.Va.) balked.

» READ MORE: How John Fetterman won Pennsylvania’s Senate race

But in practice, Sinema’s announcement may not change much, at least not immediately. And it might make Fetterman’s win even more important: Instead of just providing room to maneuver, he could, on some nominations at least, be the difference between success and failure.

Sinema said in interviews with several news outlets that her voting patterns won’t change (she already broke with her party at times), and told the Arizona Republic she’ll still caucus with Democrats, leaving them with the same power when it comes to the crucial question of controlling the chamber — which means steering committees and deciding what bills come to the floor.

It was already impossible for party-line legislation to become law over the next two years, given that Republicans are taking over the House. Any bills that make it to President Joe Biden would require bipartisan support anyway.

Even passing major legislation through the Senate alone was unlikely before Friday’s announcement, because it takes 60 votes to break a filibuster.

Critically, nominations can pass with a bare majority only, so Fetterman’s presence will still leave Democrats with enough votes if Sinema defects, provided they can keep everyone else on board and then rely on a tie-breaking vote from Vice President Kamala Harris.

(And if we’re going to be technical about it, Democrats didn’t really have 51 votes even after Fetterman flipped Pennsylvania’s Senate seat. Sens. Bernie Sanders, of Vermont, and Angus King, of Maine, are also independents who caucus with Democrats, as Sinema sounds likely to do.)

She says she’ll act less in line with Democrats than Sanders and King, but that was also already the case.

“Kyrsten Sinema is an extremely effective senator who routinely pursues pragmatic solutions with those across the partisan divide,” said Sen. Pat Toomey (R., Pa.). “That approach is increasingly unacceptable to a Democratic Party captured by the extreme left, and it is unsurprising that she feels it will be easier to represent the views of Arizonans from outside of it.”

Aides for Fetterman and Sen. Bob Casey (D., Pa.) didn’t respond to requests for comment.

The bigger issue for Democrats could arise if there’s vacancy in the next two years, which could throw the majority into doubt.

The bottom line: Democrats still have a very narrow Senate majority, and still are most likely to be tripped up by either Sinema or Sen. Joe Manchin (D., W.Va.), but they still have one more vote to work with.

» READ MORE: John Fetterman in South Philly: Make me Senate Democrats’ ‘51st vote’

What difference can 51 Senate votes make compared to 50?

Consider how Toomey blocked one of Biden’s federal reserve nominees, Sarah Bloom Raskin, earlier this year. The Senate Banking Committee, which oversaw her nomination, was evenly split to match the overall makeup of the Senate. That allowed Toomey and fellow Republicans to stall the nomination, forcing Raskin to withdraw.

With 51 votes, and a committee majority, Democrats could have at least muscled her through that panel. If Sinema does caucus with the party, they’ll retain that ability.

The biggest impact might be on Sinema’s own political prospects. She was facing a likely Democratic primary challenge in Arizona. But now, as an independent, won’t have to face that in 2024. And Democrats will have to think harder about going after her as they face a brutal 2024 map, and defend 10 potentially competitive Senate seats. If Sinema and a more liberal candidate split votes in Arizona, it could hand a swing seat back to Republicans.

Then the Democratic majority might really be in jeopardy.