WASHINGTON — For decades, conservative lobbyist Grover Norquist vowed to drive Republicans out of office if they didn’t pledge to oppose tax increases. Many lawmakers signed on.

But now, several senior Republicans are indicating they are willing to consider raising taxes as part of a deal with Democrats to avoid a catastrophic budget meltdown.

Tennessee Sen. Bob Corker says the only pledge he will keep is his oath of office. House Majority Leader Eric Cantor says no one in his home state of Virginia is talking about what leaders in Washington refer to simply as “The Pledge,” a Norquist invention that dates to 1986. Georgia Sen. Saxby Chambliss says he cares more about his country than sticking to Norquist’s pledge.

It’s a change for senior members of a party that long has stood firmly against almost any notion of tax increases. Republican legislators and Democratic President Barack Obama’s White House are haggling vigorously as they look for ways to reach agreement on detailed tax adjustments and spending cuts before automatic changes occur.

The naysaying about the pledge is raising the question of whether Norquist is losing his position of power within the GOP. It’s a notion that he calls ridiculous. “Nobody’s turning on me,” Norquist said Monday.

But he indicated he would turn on lawmakers who defy him, starting with Corker, who Monday published an opinion piece in The Washington Post outlining an alternative to the budget breakdown that includes more taxes.

“Corker was elected to the Senate because he took the pledge,” Norquist said on Fox News. “He would not be a senator today if he hadn’t made that commitment. If he breaks it, he’s going to have to have a conversation with the people of Tennessee about his keeping his word. And the same thing with other people who are elected because they made that written commitment to the people of their state.”