There is a trend that Senate Democrats vulnerable for reelection in 2024 are starting to drift away from voting with President Joe Biden.
Chief among them is Sen. Joe Manchin of West Virginia, a state which former President Donald Trump won by nearly 40 percentage points over Biden in 2020. Although Manchin has yet to announce plans to seek reelection, he has voted with Biden's position on a bill or resolution just 21.4% of the time in the 118th Congress, which started Jan. 3 — a drop of 66.5 percentage points from the 117th Congress, according to an analysis by FiveThirtyEight.
Sen. Jon Tester of Montana, a state which Trump carried by nearly 17 points in 2020, went from voting with the president 91% of the time in the 117th Congress to just 50% of the time in the 118th Congress.
"While most Democratic senators still agree with Biden over 80% of the time, these declines are significant," wrote Cooper Burton of FiveThirtyEight. "As a whole, Democratic senators are voting Biden's way 11 points less than in the last Congress."
FiveThirtyEight's data includes all votes through June 20 for which Biden or the White House had an official position — a total of 14 votes, except district and appellate court confirmations.
Another vulnerable senator is Krysten Sinema of Arizona, elected as a Democrat in 2018 but is now an independent who caucuses with Democrats. Trump lost Arizona by 10,477 votes in 2020. Sinema has voted with Biden 71.4% of the time this year, compared to 93.9% in the 117th Congress.
In other battleground states, Jacky Rosen of Nevada has gone from 92.9% in the 117th Congress to 71.4% this year — Trump lost Nevada by 33,596 votes in 2020; Sherrod Brown of Ohio and Bob Casey of Pennsylvania each went from 98.5% to 78.6%; Trump won Ohio by eight points in 2020 and lost Pennsylvania by 80,555 votes.