Much ink has been spilled trying to understand what’s motivating senators Kyrsten Sinema (D-AZ) and Joe Manchin (D-WV) to try to gut so many of the popular progressive policies in Democrats’ health care, climate, and anti-poverty spending bill. Why would the senators be so content angering their base and potentially threatening their chances of winning reelection down the road?

During the fight over Democrats’ social spending reconciliation bill, Sinema, for example, has played a prominent — albeit silent — role in watering down the party’s plan to allow Medicare to negotiate prescription drug prices. She’s also helped gut Democrats’ plan to expand Medicare benefits, nixed tax hikes on the wealthy and corporations, and pushed to make the overall bill smaller. While Sinema isn’t up for reelection until 2024, she is polling terribly and already facing the threat of a well-financed primary challenge.

While Manchin has a personal financial interest in protecting the fossil fuel industry, he’s also worked diligently to deny new Medicare dental benefits that seniors in his state desperately need. Manchin has been on a fundraising tear this year, despite stating last week that he hasn’t decided whether he’ll run for reelection in 2024.