As they look ahead to 2008, some conservative Republicans are bemoaning the lack of a “real” conservative in the growing presidential field.

A veteran Texas Republican pollster, David Hill, devoted his weekly column in the Capitol Hill publication The Hill last week to that concern. And recent polls showing former New York Mayor Rudy Giuliani and Arizona Sen. John McCain topping the GOP field can’t be reassuring to the party’s dominant faction.

Hill dismissed the candidacies of McCain, who has a solid conservative record on most issues, and outgoing Massachusetts Gov. Mitt Romney, who has made a big play in recent months for conservative support. He cited two “big-name, true-blue conservatives” who would fit his bill: former Texas Sen. Phil Gramm and former Vice President Dan Quayle.

He called Gramm, who flopped in a 1996 presidential bid, “a ferocious fundraiser who’d really get conservatives in a lather if he decided to run.” And he characterized Quayle, who abandoned his 1996 race on health grounds, as “an interesting thought.”

There’s no sign that either the GOP electorate or the two men themselves are interested in their running. Their last political outings hardly demand an encore.

But Hill’s column reflects a growing dilemma among GOP conservatives who fear they face this unpalatable choice in 2008: Do they support someone who pledges fealty to conservative principles but whom they fear may not really mean it? Or do they keep looking for the “real” thing?

In dismissing McCain and Romney, Hill conceded that they “possess some conservative credentials” but said “neither of them seems particularly interested in being the ‘real’ conservative.”

“They are already moving to the center to win the general election, and this could be their undoing if a genuine conservative enters the fray,” the Texas pollster added.

That’s not entirely true, especially in the case of McCain. Indeed, some people who regard the Arizona senator as the party’s strongest candidate fear he may already be moving too far right to appeal to the independents any GOP candidate needs to win.

Though he opposed the 2001 Bush tax cut, one of several issues conservatives hold against him, he says now he would vote to make the cuts permanent. And he made up last year with the Rev. Jerry Falwell, whose influence he assailed during his 2000 presidential bid.

Many conservatives still blame McCain for the 2002 campaign reform act, which they regard as an assault on free speech.

But that enmity may be overcome by his fervent support of the U.S. role in Iraq and his repeated calls to increase U.S. troop strength, something President Bush may be about to do.

One result of his moves to strengthen himself among conservatives is that, according to the most recent ABC News-Washington Post poll, McCain’s favorability among independents has dropped 15 points in the past year.

Romney is also stressing his conservative credentials, especially on the issue of gay marriage. He recently called on the Massachusetts Supreme Court to place a referendum banning gay marriages on the 2008 ballot.

But he came under some conservative fire when a 1994 letter emerged in which he said the GOP should take the lead in ensuring “equality for gays and lesbians.”

That was during his unsuccessful Senate race against Sen. Edward Kennedy when he supported keeping abortions legal, a position he has now changed.

Three potential conservative standard-bearers have already eliminated themselves: Retiring Sen. Bill Frist of Tennessee decided not to run after a less-than-successful tenure as Senate majority leader. Sens. George Allen of Virginia and Rick Santorum of Pennsylvania lost re-election bids.

Allen’s defeat from self-inflicted wounds came as the Virginia senator had already started mapping a White House race.

Two lesser-known hopefuls are seeking the conservative mantle: Kansas Sen. Sam Brownback and Arkansas Gov. Mike Huckabee. They didn’t even rate dismissal by Hill.

In a sense, what GOP conservatives face in 2008 is nothing new. Since the candidacy of Barry Goldwater, the most conservative contenders – like Phil Crane, Alan Keyes and Gary Bauer – have never won a GOP nomination. Conservatives have generally had to settle for more mainstream candidates, enthusiastically for Ronald Reagan and George W. Bush, less so for Gerald Ford, the elder George Bush and Bob Dole.

That may well happen again in 2008.

Carl P. Leubsdorf is Washington bureau chief of The Dallas Morning News.