Former New York City Mayor Rudy Giuliani speaks at the Churchill Club in Santa Clara, Calif., on Feb. 12. (AP Photo/Paul Sakuma)

Rudy Giuliani's candidacy has dismayed conservative Republicans who question whether a man accused of being an adulterer is presidential material.

The former New York City mayor has led the field for the 2008 Republican presidential nomination, but conservatives, particularly in the evangelical community, are gearing to block his nomination. Although Giuliani has supported abortion and gay rights, his personal life has sparked the most concern, and conservatives say this could help the presidential campaign of Sen. Hillary Rodham Clinton, New York Democrat.

"He may not have the confidence of conservative voters," said Keith Thompson, a conservative analyst and author.

Thompson, author of "Leaving the Left: Moments in the News That Made Me Ashamed to be a Liberal," said Giuliani, mayor during the 9/11 attacks, has sought to move to the right on what began as liberal positions on abortion, gay rights and gun control. Thompson said that Giuliani's shift was opportunistic.

Giuliani has led the field for the 2008 Republican nomination and the latest polls say he would defeat Clinton if the presidential election were held now. Analysts said Giuliani has eclipsed Sen. John McCain, Arizona Republican, who engenders more opposition among conservatives than the former mayor.

A leaked memo that detailed Giuliani's campaign strategy has indicated his shift from the left. The memo questioned his positions as well as Giuliani's previous marriages and allegations regarding his former business partner, ex-New York City police commissioner Bernard Kerik.

The memo envisioned problems regarding Giuliani's nasty divorce from television reporter Donna Hanover. The divorce came amid allegations that Giuliani was having an affair with his third and current wife, Judith Nathan.

"We're talking about a self-admitted moderate GOPer who, in his third marriage, split from his last wife in a high-profile manner that was chronicled in People Magazine," said Jon Fleischman, a leading political consultant and founder of FlashReport.org. "He is pro-choice, supports civil unions, and embraces an amnesty/guest worker program for criminal aliens."

Analysts said evangelical conservatives have not decided on Giuliani. They said many of them believe that Giuliani marked the only hope of Republicans to defeat Clinton in 2008 and was preferable than McCain.

"I would not vote for John McCain under any circumstances," Focus on the Family founder James Dobson said in an interview to a Christian radio station in January. "I pray that we won't get stuck with him."

A memo by Giuliani's strategy director Brent Seaborn asserted that 76 percent of white evangelical Christians supported the former mayor. Seaborn also said internal polls show 82 percent of conservative Republicans also endorsed Giuliani. However, there have been no independent polls taken that confirm those high numbers.

But analysts said Clinton would prefer Giuliani for the GOP presidential nomination. They said that, in any race, Clinton could argue that her marital record was better than the thrice-married Giuliani.

"Neither side in a Clinton-Giuliani face-off would want the subject of adultery to come up. But the Clintons could point out that they stayed married," said Craig Crawford, a news analyst for major television networks.