A proposed $1.5 billion cash infusion for the D.C. Metro has Republican conservatives crying foul and trying to make life difficult for its GOP sponsor, Rep. Tom Davis.

Davis — who represents the Northern Virginia suburbs and may run statewide as soon as 2008 — has been trying for years to enact a long-term funding package for the transit system, but he faces a family feud with conservatives who want to derail what they consider to be pork on a massive scale.

Rep. Jeb Hensarling (Texas), the chairman of the conservative Republican Study Committee, attacked the earmark as the “largest in American history,” far larger than the “bridge to nowhere” in Alaska, and aims to rally Republicans against it when it reaches the House floor.

“I think it’s an important vote to let the American people know, will Republicans act like Republicans or will it be business as usual?” Hensarling said Tuesday. “The last thing we need to have is what the Heritage Foundation and others have said is the largest earmark in history.”

Rep. Patrick McHenry (R-N.C.) temporarily blocked the bill in committee before the April recess on procedural grounds. “I know this is Washington, but $1.5 billion is still a lot of money,” McHenry said. “Are D.C. pork projects really a top priority given the challenges we face as a nation?”

The stalling tactic isn’t likely to slow the bill for long.

Despite the internecine war among Republicans, prospects appear good for passing the bill through the House again, with backing from powerful Washington-area Democrats including House Majority Leader Steny Hoyer and Democratic Congressional Campaign Committee Chairman Chris Van Hollen, both of Maryland.

Davis said Tuesday he’s confident his authorizing bill will become law this year after a similar measure passed the House last year only to be shelved in the Senate.

“It’ll become law,” he predicted, noting bipartisan support in both chambers and last year’s 242-120 House vote on a similar Metro funding bill, including 83 Republicans. “This should be pretty easy. … We’re going to always have people who don’t want to spend money except in their districts.”

Criticism from conservatives of transportation initiatives “is one of the reasons Republicans have struggled in Northern Virginia,” said Davis, who plans to run for Senate next year if Sen. John Warner (R) decides not to run for re-election and who also has been mentioned as a potential gubernatorial candidate.

Davis said his fellow Republicans need to understand that transportation is the No. 1 issue facing the region.

“I think if they want to be competitive, they can be for it; if they don’t want to be competitive [in Northern Virginia] — it’s a third of the state — they can vote against it,” Davis said.

And Davis argues that the national interest is clear.

“You’ve got to have a Metro system in the nation’s capital,” he said. “If there is a terrorist strike, you are going to need a strong Metro system.”

Stephanie Lundberg, a spokeswoman for Hoyer, also came to the bill’s defense. “It’s really kind of unfortunate,” she said of the criticism from Republican Members. “It would be helpful for those offices to survey their staffers on how they get to work and how their visitors get around.”

The bill would authorize $1.5 billion more for Metro over the next decade coupled with tougher federal oversight of the transit system and a requirement for matching funds from Virginia, Maryland and the District of Columbia. The money still would require annual appropriations.

The Washington Metropolitan Area Transit Authority and its supporters have argued that it needs the money for rail cars and other improvements to keep pace with growth in the system and maintenance, but critics such as the Heritage Foundation’s Ronald Utt argue that cost-cutting and fare hikes should come first.

“You are subsidizing what for the most part are reasonably well-off public employees coming in from the suburbs,” Utt said. “These are hardly people that need to be subsidized by the rest of Virginia. … There seems to be little sense to justify what I call a trickle up subsidy.”

But Davis said the need for the cash infusion has been confirmed by independent studies and said the bill’s provisions already have prompted Metro to take steps to improve efficiency, such as hiring an inspector general.

“If this bill were not out there, I don’t think it would have happened,” Davis said.

The internal dispute over the bill also extends to state party politics, where battles over transportation funding have split the GOP for years along geographic lines. Six of Davis’ seven Republican House colleagues in the state delegation voted against last year’s Metro funding bill, with the exception of fellow Northern Virginia Rep. Frank Wolf.

That could have implications for next year’s Senate race. Davis’ moderate record has irked conservatives for years, but his strength in the voter-rich Washington suburbs, a growing Democratic stronghold, could hold the best chance of keeping the Senate seat Republican, particularly if popular former Democratic Gov. Mark Warner joins the race.

State conservative groups such as the Virginia Club for Growth blasted Davis, charging that the requirement for matching funds will lead to an increase in state and local taxes.

“The Davis earmark is outrageous,” said Phillip Rodokanakis, president of the Virginia Club for Growth. “It makes the ‘bridge to nowhere’ pale by comparison. Metro is broke and if anyone is serious about fixing it, they should consider privatizing it, not giving it more government dole.”

But Davis counters that Virginia’s Legislature overwhelmingly approved a transportation bill that would fund the state’s share.

“Virginia has spoken,” Davis said. “Everybody’s on board.”

Although criticism of Metro funding could provide fodder for a conservative running against Davis in a competitive statewide Republican primary, the federal lucre also would be a huge boon for Davis’ Northern Virginia base and in a general election as Davis seeks to appeal to suburban commuters.

“I don’t think it has anything to do with anything statewide … but it has a lot to do with my constituents in Northern Virginia,” Davis said of the bill. “I don’t think people in Norfolk care.”

Another Davis bill, one that would grant voting rights in the House to the District of Columbia and an additional House seat to Utah, also fell prey before the break to procedural motions from fellow Republicans, who sought to amend it to repeal the District’s handgun ban. That legislation is expected back on the House floor next week.