WASHINGTON — Senate Republicans killed legislation yesterday aimed at removing limits on how long workers can wait before suing their employers for pay discrimination.

Democrats, speaking to key constituencies of women, minorities and swing voters this election year, said they weren’t finished trying to pass the bill.

“Women of America: Put your lipstick on, square your shoulders, suit up” and get ready to fight, Senator Mikulski, a Democrat of Maryland, said moments after the bill’s opponents denied supporters the 60 votes needed to proceed to full debate and a vote on passage. “The revolution starts tonight.”

Debate on the legislation, which was proposed in response to a Supreme Court decision last year, was steeped in election-year politics and shadowed by a White House veto threat.

The vote sparked dueling news conferences yesterday in which leaders of both parties accused each other of playing politics with key voting blocs in a year when the presidency, every House seat, and a third in the Senate are on the ballot.

Democratic presidential rivals senators Clinton and Obama swung through Washington to speak from short, prepared statements in favor of the legislation. It was the first time in months that both candidates spoke on the Senate floor, an indication of the bill’s importance to voters the two are fighting for in their ongoing battle for their party’s nomination.