Chambliss was already going to face a challenger in his primary in 2014 thanks to his membership on the "Gang of 8." But his parting shot at Grover Norquist is a harbinger of things to come. Going against Norquist just isn't as risky as it used to be.

Reuters:

"I care more about this country than I do about a 20-year-old pledge," Chambliss told Georgia television station WMAZ on Thursday. "If we do it his way, then we'll continue in debt, and I just have a disagreement with him about that."

Chambliss, who represents Georgia, is a member of the so-called Gang of Eight group of senators, a bipartisan alliance working for deficit reduction, formed last year when the country was on the verge of default thanks to a partisan battle over raising the country's borrowing limit.

A vast majority of elected Republicans have signed the pledge Norquist created in 1986, which commits them to voting against tax increases, and it became a type of litmus test among U.S. conservatives.

But its influence, and that of Norquist's organization, Americans for Tax Reform, may be waning following Republican losses in this month's elections and acknowledgments from Republican leaders that revenue must be raised to pare deficits topping $1 trillion.

"Grover Norquist has no plan to pay this debt down. His plan says you continue to add to the debt. I just have a fundamental disagreement with him about that," Chambliss said.

Norquist, in response, noted that Chambliss was an author of an open letter to him last year from three Republicans promising support for revenue generation from the "pro-growth effects" of lower tax rates.

"Senator Chambliss promised the people of Georgia he would go to Washington and reform government rather than raise taxes to pay for bigger government," Norquist said.

Some Republicans contend they are only open to raising revenue through economic growth, an impact hard to quantify and which Democrats and many economists say is not nearly enough.

Republican aides on Capitol Hill have been grumbling privately about the attention Norquist gets, worrying that it weakens their ability to negotiate across the aisle.

Speaker Boehner and House Republicans appear to be holding the line on taxes so far. But the pressure to cave on tax increases is going to be tremendous if a significant number of Republicans jump ship. As long as the party is united on the issue, they won't suffer much as a result of their stand on taxes - even if it means going over the fiscal cliff.

But if a dozen or two Republicans vote with the Democrats, it will place a lot of House members in jeapardy in a general election. It will be tough to explain why some Republicans compromised while others didn't.