Oct. 18 (Bloomberg) -- When thousands of evangelical Christians gather at the Values Voters Summit today to judge -- and potentially condemn -- the Republican presidential candidates, the ghost of an 18th-century French philosopher will be haunting the corridors of the Washington Hilton.

``I am asking them to at least consider Voltaire's question: Do you make the perfect the enemy of the good?'' said Richard Land, a leader of the 16-million-member Southern Baptist Convention, based in Nashville.

The evangelical movement, which has been a major force in the Republican Party since helping Ronald Reagan's presidency, is struggling this year. The movement's leaders can't agree on which candidate is best suited to stop the current front-runner, former New York Mayor Rudy Giuliani, who has a record of support for abortion and gay rights.

They are also divided on whether to field a third-party candidate if Giuliani wins the Republican nomination, which may deliver the White House to Senator Hillary Clinton of New York, who is leading the Democratic pack.

There has always been a difference of opinion between ``standing on principle and being pragmatic enough to win an election,'' said Ralph Reed, the former executive director of the Christian Coalition. ``That tension has been brought into full relief by this election cycle.''

`Mystified'

The pragmatists are ``mystified'' that Christian conservatives aren't more concerned by the prospect of a Clinton restoration to the White House, said Gary Bauer, who ran for his party's nomination in 2000 on a pro-life platform.

If Clinton, 59, wins, ``her administration would declare war on social conservatives,'' Bauer said. ``She'll go after conservative talk radio, she'll go after Christian radio.''

At the other end of the spectrum is James Dobson, founder of the Focus on the Family, an evangelical organization in Colorado Springs, Colorado. He, along with 50 other influential movement leaders, pledged two weeks ago to vote for a ``minor- party candidate'' if both the Republican and Democratic nominee is pro-choice.

``Some leaders will hold to principle and will not vote for someone who is pro-abortion,'' said Tom Minnery, the political director of Focus on the Family.

Straw Poll

Many conservatives are counting on a straw poll at this week's conference to help them coalesce around an anti-Giuliani candidate. ``You'll see one or two candidates emerge after the event and you'll see some solidifying,'' said Tony Perkins, president of the Family Research Council, which is hosting the four-day summit.

Giuliani, who will address the summit Oct. 20, has the biggest hurdles. His support for abortion rights, gay rights and gun control -- and his three marriages -- run counter to the core positions held by evangelical voters.

Land said these concerns haven't been allayed by Giuliani's promise in March to appoint ``strict constructionist'' judges to the federal bench, which abortion foes interpret as a code for support for the eventual outlawing of the procedure.

``He also promised two previous wives that he would love, honor and cherish them until death do us part,'' Land said.

There is also little enthusiasm for the other leading Republican candidates. Former Tennessee Senator Fred Thompson, who entered the race last month initially generated excitement among evangelicals, though that waned after he admitted that he doesn't attend church regularly, and said that if a state chose to recognize gay marriage, then ``so be it.''

McCain

For their part, Arizona Senator John McCain and former Massachusetts Governor Mitt Romney have failed to convince Christian conservatives that they can be trusted. McCain, 71, who went out of his way to criticize evangelical leaders when he ran in 2000, has done little to make amends. He also was a sponsor of campaign-finance legislation that many evangelicals view as limiting their political influence.

Romney, 60, has reversed his earlier support for abortion rights and made opposition to gay marriage a centerpiece of his campaign, though he must still grapple with deep distrust of his Mormon faith among evangelicals.

Giuliani, 63, may yet be able to neutralize Christian- conservative opposition by giving them a role in selecting his running mate and by signing a formal pledge to take their views into account on a range of issues, from judges to abortion to gay rights.

`Negotiations'

Bauer said that with some ``serious negotiations'' over his platform, religious conservatives could find a way to support Giuliani. He declined to provide specifics, citing a need to maintain his bargaining position if Giuliani is the Republican nominee.

Much of the mistrust of Giuliani stems from his track record, particularly his opposition in 2000 to a ban on so- called partial-birth or late-term abortion, though he recently modified that position. He is also criticized for granting marriage-like benefits to the domestic partners of gay New York City employees.

Michael Farris, the chancellor of Patrick Henry College, an evangelical school in Purcellville, Virginia, said he would consider supporting Giuliani only if ``he named my mother as vice president.''

`Influence'

Still, some evangelical leaders doubt they will be able to make good on the threat to bolt the Republican Party. ``It's not at all clear that the so-called leaders can influence that constituency one way or the other,'' said Phyllis Schlafly, president of the Eagle Forum, based in Alton, Illinois.

One Republican candidate, Mike Huckabee, a former governor of Arkansas and an ordained Baptist minister, has emerged as an ideal choice for Christian conservatives on all the issues. Still, his support is only in the low single digits in national polls and he hasn't been able to raise money.

The soul-searching has also set evangelicals apart from fiscal conservatives, who say the Christian leaders are bluffing. ``The entire conservative movement is going to be united because Hillary is going to be on the ballot and the Supreme Court is going to be at stake,'' said Grover Norquist, president of Americans for Tax Reform, a Washington-based anti- tax advocacy group.

Land sees things differently. ``I know a lot more evangelicals than Grover does,'' he said. ``If Giuliani is the nominee, Grover will be shocked.''

To contact the reporter on this story: Hans Nichols in Washington at hnichols2@bloomberg.net

Last Updated: October 18, 2007 00:06 EDT