WASHINGTON - Republican contenders in the 2008 presidential race tried to woo a tough crowd on Friday at a summit for "values voters": conservative Christians who have yet to rally around a single candidate.

Comprising mostly white evangelical Protestants known loosely as the "religious right," the group is an important part of the Republican base, credited with securing two White House terms for President George W. Bush.

But their influence within the party has been questioned by the showing of former New York Mayor Rudy Giuliani, who is leading national Republican polls despite his support of abortion and gay rights -- positions anathema to the movement.

Stridently anti-abortion Republicans cannot even contemplate this happening.

"He's (Giuliani) is not going to be the nominee. The party is not going to nominate a pro-choice candidate," Kansas Sen.r Sam Brownback told reporters after he addressed close to 2,000 delegates and activists.

The conservative Senator was expected to announce that he was dropping out of the presidential contest Friday in Kansas, slightly narrowing the field of Republicans courting the religious right.

All nine main Republican contenders were to address the summit.

Arizona Sen. John McCain stressed his anti-abortion credentials - a refrain that is sure to become a familiar one as the candidates attempt to paint themselves as "anti-Giulianis" on this crucial Republican issue.

"I have been pro-life my entire public career. I believe I am the only major candidate in either party who can make that claim," McCain said.

ROMNEY'S RELIGION

Some evangelicals are throwing their support behind former Massachusetts Gov. Mitt Romney, a recent convert to the anti-abortion cause. His biggest drawback in the view of some analysts is his Mormon faith.

A recent survey by the Pew Research Center found that 52 percent of white evangelicals who attend church on a weekly basis did not view the Mormon faith as Christian.

But some evangelical activists say they have much in common with followers of the Church of Jesus Christ of Latter-day Saints, as the faith is officially known. Mormons are socially conservative and tend to vote Republican.

"We are electing a president and not electing a pastor. You are not going to see any difference between a Southern Baptist family and a Mormon family on family values," said David French, one of the co-founders of Evangelicals for Mitt.

Other anti-abortion social conservatives such as Texas Gov. Rick Perry have embraced Giuliani because they say they agree with most of his positions and that it is not necessary to agree rigidly on every thing.

"Giuliani has come across as strong on the war on terrorism and he has signaled strong support for Israel and these positions appeal to evangelicals," said Scott Keeter of the Pew Research Center.

Nationally known social conservatives such as Focus on the Family founder James Dobson have said they will back a third-party candidate if Giuliani gets the nomination.

That may highlight the limits of their current influence within the Republican Party, which some analysts say has been curtailed by emerging evangelical divisions on other issues such as the environment, health care and poverty.