(NewsNation) — A group of veterans is staging a sit-in at the Capitol in response to Senate Republicans blocking a bill that would extend health care benefits to millions of veterans who were exposed to toxins during their service.

“If they can’t get a really important, urgent piece of veteran’s legislation done, then what can they get done,” said Paul Rieckhoff, Founder of Iraq and Afghanistan Veterans of America (IAVA), in reaction to U.S. Senate Republicans blocking a bill to provide healthcare for veterans exposed to toxic burn pits while serving abroad.

Twenty-five senators went from supporting the Sgt. 1st Class Heath Robinson Honoring Our PACT Act when it passed the Senate 84-14 last month to helping filibuster the bill when a technically updated version was blocked 55-42 on Wednesday.

“Heroes will die because of these delays in Washington,” Rieckhoff said.

Comedian Jon Stewart, an outspoken advocate for military veterans, erupted in anger after the vote.

“I’m used to the lies, I’m used to the hypocrisy, I’m used to the cowardice, I’m used to all of it, but I am not used to the cruelty,” Stewart told reporters outside the Senate during a news conference called by the bill’s advocates.

Watch the full interview with Paul Rieckhoff in the video player at the top of the page.

The Hill contributed to this report.