Senator Manchin is Out. Where Does That Leave the Senate After 2024?

Ryan Heshmati

November 10, 2023

The Democratic Party may be losing its grip on the Senate. On November 9, Joe Manchin announced he did not intend to run for re-election for his senatorial seat in West Virginia. Incumbents retiring may not be particularly notable most of the time, but with Manchin’s seat, it is. Senator Manchin, formerly governor of West Virginia, holds one of the most decisive votes in the 51-49 Democratic majority-held U.S. Senate, which is already on flimsy ground with Kyrsten Sinema’s switch to being an Independent in late 2022. He is also a Democrat holding a Senate seat from one of the most conservative states in the nation. With his seat open, Democrats in the Senate are in trouble. 

In 2024, seats are open in key states for Republicans like Montana, Ohio,, Arizona, and Nevada. The GOP has the opportunity to flip the Senate with a net gain of two seats. If Manchin’s seat goes to the Republicans, which it very well could do, that requires Republicans to gain in just one other state.

Montana, a state that Donald Trump carried by a margin of over 16 points, has a Democrat, Jon Tester, up for re-election and could be where Republicans strike. Widely regarded as a tossup, Tester’s race is likely to be incredibly close, with no past victory of Tester’s, who took the seat in 2006, handed him even 51% of the vote. 

Democrats’ troubles do not stop there, however, as Arizona, a once reliably Republican state, has Kyrsten Sinema’s seat up for grabs. Sinema, who has left the Democratic party since her 2018 victory against Martha McSally, may or may not run for re-election. Regardless of who the candidates are, though, Republicans have a shot at taking back what once was Republican Senator Jeff Flake’s Senate seat.

To make matters worse for Democrats, Sherrod Brown of Ohio is up for re-election, and, despite winning in 2018 with a healthy margin of nearly 7 points, there is great concern among Democrats as to whether Republicans could take the seat. Part of the reason for concern is that, in 2022, Republican J.D. Vance secured victory over Ohio’s other Senate seat. Senator Brown is running in a state that both President Obama and President Trump carried, leaving Brown’s fate uncertain.

There is almost a year left until the 2024 election, and while many may focus on the presidential race, the results in the Senate will also be incredibly significant. With Democrat Joe Manchin not seeking re-election and a Republican successor likely in the eyes of many, Democrats have several races they will need to pull through in to prevent a Republican majority in the Senate.