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 breaking ranks, willing to consider raising more money through 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 quite an about-face for senior members of a party that long has stood firmly against almost any notion of tax increases. And while GOP leaders insist they still don't want to see taxes go up, the reality of a nation in a debt crisis is forcing some to moderate their opposition to any movement on how much Americans pay to fund their government. 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, blunt-force changes occur at the new year.

"Oh, I signed it," Sen. Jeff Sessions said on Fox News about Norquist's pledge. "But we've got to deal with the crisis we face. We've got to deal with the political reality of the president's victory."

The naysaying about the pledge is raising the question of whether Norquist -- a little-known Republican outside of Washington -- 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 revenue.

"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."

At the White House, spokesman Jay Carney said Monday that the shifting away from Norquist signaled an opportunity for Republicans to work with President Obama.

"They represent what we hope is a difference in tone and approach to these problems and a recognition that a balanced approach to deficit reduction is the right approach," Carney said.

Norquist, the head of the conservative Americans for Tax Reform, opposes tax increases of any kind, whether eliminating deductions, a position some GOP lawmakers say they're open to, or raising rates. He has insisted on hardline positions from lawmakers and, for years, has held outsized sway in the party for someone who does not hold public office. His pledge doesn't allow any change to the tax code that adds a dollar to revenues.

House Speaker John Boehner has called that notion unrealistic and has dismissed Norquist as "some random person."

Nevertheless, Norquist has maintained a certain level of clout for years.

Heading into the 2012 elections, 279 lawmakers had signed Norquist's' pledge, according to Americans for Tax Reform.

But some who have signed the pledge are having second thoughts. And when the new House is seated next year, no more than 212 of them consider themselves bound by the promise.

"I'm not obligated on the pledge," Corker told CBS News. "I was just elected. The only thing I'm honoring is the oath I take when I serve when I'm sworn in this January."

He's not alone in his stance on the pledge.

"When I go to the constituents that have re-elected me, it is not about that pledge," Cantor said on MSNBC. "It really is about trying to solve problems."

Chambliss, a veteran senator from Georgia, said he signed the pledge during an earlier campaign when the country's debt was nowhere near its current $16 trillion level.

"Times have changed significantly, and I care more about my country than I do about a 20-year-old pledge," Chambliss told his local television station. "If we do it (Norquist's) way, then we'll continue in debt."

"I'm frankly not concerned about the Norquist pledge," Chambliss added.

Raising taxes, whether by closing loopholes or raising tax rates, is seldom a vote-winning strategy.

President George H.W. Bush broke his campaign promise to not raise taxes; he ended up losing re-election 1992.

Other Republicans, however, now are willing to put additional tax revenues on the table as a bargaining chip for a deal with Democrats to get changes in Social Security and Medicare and pare down federal deficits.

"I agree with Grover, we shouldn't raise rates. But I think Grover is wrong when it comes to we can't cap deductions and buy down debt," Sen. Lindsey Graham of South Carolina said Sunday on ABC's "This Week."

"I will violate the pledge -- long story short -- for the good of the country, only if Democrats will do entitlement reform," he added.

Rep. Peter King of New York told Sunday's "Meet the Press" on NBC that the pledge is good for a two-year term only.

"A pledge you signed 20 years ago, 18 years ago, is for that Congress," King said. "For instance, if I were in Congress in 1941, I would have signed a support of declaration of war against Japan. I'm not going to attack Japan today. The world has changed, and the economic situation is different."

And Sen. John McCain, his party's presidential nominee in 2008, said the pledge is losing its clout.

"Fewer and fewer people are signing this, quote, pledge," he told an audience recently.