Anti-tax warrior Grover Norquist on Monday warned Virginia lawmakers that they would be backing a "job-killing tax increase" if they agreed to tie the gas tax to inflation to generate additional funding for roads.

Norquist, the president of Americans for Tax Reform whose no-tax pledge has been signed by many Republicans, is on a collision course with Virginia Gov. Bob McDonnell, a Republican who said allowing the gas tax to rise with inflation isn't a tax increase.

McDonnell is set to unveil his transportation plan next week, and, while he hasn't revealed how he'd raise the $500 million in new money that he seeks, he specifically mentioned the possibility of indexing the gas tax to inflation. Unlike the sales tax, which is a percent taken at the register, the gas tax is 17.5 cents for every gallon sold, no matter the price.

Norquist is trying to head off that possible increase before the General Assembly even convenes to consider it.

"For those members of the Virginia Legislature who have signed the Taxpayer Protection Pledge," Norquist wrote to lawmakers, "voting to index the gas tax to inflation, without [corresponding budget cuts] would be in clear violation of the promise you made to your constituents and the people of Virginia to oppose any and all efforts to increase taxes."

About 30 Virginia Republicans -- including Lt. Gov. Bill Bolling and Attorney General Ken Cuccinelli -- have signed the no-tax pledge, but McDonnell has not.

A McDonnell spokesman declined to comment on the specifics of Norquist's letter but said the governor "appreciates all the input on this issue that he has been receiving."

Norquist has asked every state and federal candidate since 1986 to sign an oath promising never to raise any tax, and his group enforces it by campaigning against those who break the pledge or refuse to sign it.

But Norquist's standing has never been shakier. Congressional Republicans, almost all of whom have signed his pledge, are now saying they may break it as part of a compromise on deficit reduction that's needed to avoid the so-called fiscal cliff, a set of massive tax increases and spending cuts set to take effect Jan. 1. And some Virginia Republicans sound just as willing to buck Norquist.

"[Norquist] doesn't have to solve any problems. He just can complain," said Del. Dave Albo, R-Springfield, who first signed the pledge in 1993. "That's my problem with him. I understand if he said raising the gas tax, or raising another transportation-oriented fee, is a tax increase, but he's just completely wrong on this."

Democrats are annoyed that Norquist is weighing in just as bipartisan support was emerging to tackle the state's transportation woes.

"Where does he propose cutting money? Medicaid, which is ranked 48th out of 50 in the nation [in Virginia]? Our existing transportation system, which has reached a point of crisis? K-12 education?" asked Del. Bob Brink, D-Arlington. "What he has to say is absurd."