Five military veterans resigned from Sen. Kyrsten Sinema’s advisory board this week, calling her one of the “principal obstacles to progress,” who is more responsive to donors than constituents.

In a searing letter addressed to Sinema – obtained by The New York Times – the veterans accuse the Arizona democrat of “hanging your constituents out to dry” by opposing the elimination of the filibuster and blocking President Joe Biden’s social spending plan.

“You have become one of the principal obstacles to progress, answering to big donors rather than your own people,” the letter continues. “We shouldn’t have to buy representation from you, and your failure to stand by your people and see their urgent needs is alarming.” 

Sylvia González Andersh, one of the letter’s signees, reads parts of it in a forthcoming ad funded by Common Defense, a progressive veterans’ activist group.

Andersh told The Times in an interview:

Democrats were out desperately trying to help her win the seat, and now we feel like, what was it for? Nobody knows what she is thinking because she doesn’t tell anybody anything. It’s very sad to think that someone who you worked for that hard to get elected is not even willing to listen.

In a statement, Sinema told The Times she would “always remain grateful for these individuals’ service to our nation.” She added: “While it is unfortunate that apparent disagreement on separate policy issues has led to this decision, I thank them for their service and will continue working every day to deliver for Arizona’s veterans who have sacrificed so much to keep us safe and secure.” 

Sinema and West Virginia Senator Joe Manchin are the lone Senate Democrats who opposed a $3.5 trillion dollar package that funds liberal priorities like universal pre-k, free community college, paid family leave, expanded healthcare, and programs designed to combat climate change.

Democrats have paired back the plan – by reportedly jettisoning free community college and a clean energy program – in order to gain the holdouts’ support, which is necessary in an evenly-divided Senate.

But according to The Wall Street Journal, Sinema also opposes the tax increases that would fund the new spending. Democrats are currently negotiating alternative funding methods.