Veterans groups were ready to celebrate the final passage of landmark legislation expanding health benefits to service members exposed to toxic chemicals – until the bill’s last-minute defeat late Wednesday.

The Senate previously approved almost identical legislation, and Wednesday’s vote to clear up a technical change seemed to be on its way to passage until 25 Republican senators changed their votes, blocking the bill’s advancement.

“This delay might not sound like a big thing, but number one, we don’t have the bill passed, and number two, there are going to be veterans die between now and when this bill passes,” Senate Veterans Affairs Committee Chair Jon Tester (D-Mont.) said.

The Sergeant First Class Heath Robinson Honoring Our PACT Act would add 23 illnesses to the list of conditions assumed to be service-connected for those who were exposed to toxic burn pits, Agent Orange and other toxins. It would impact an estimated 3.5 million veterans.

Sen. Pat Toomey (R-Penn.) objected to the bill because of a funding mechanism and got enough backing from his colleagues to hold it up. He said he still supports the substance of the bill.

But Veterans Affairs Committee Ranking Member Jerry Moran (R-Kan.), who voted in favor of the bill Wednesday, admitted that some of his colleagues were likely upset over an agreement Sen. Majority Leader Chuck Schumer (D-N.Y.) and Sen. Joe Manchin (D-W.V.) announced around the same time on an unrelated bill.

“There may have been emotion,” Moran told reporters, according to Military.com.

There was emotion from veterans advocates, too.

“The next time I come back here, it better be to sign the damn bill at the White House, because I’m sick and tired of this bulls—,” Susan Dyer, the mother-in-law of the bill’s namesake, said at a press conference outside the Capitol.

Marine Corps photograph by Cpl. Samuel D. Corum