WASHINGTON — In what may be one of the most important speeches of his campaign thus far, Mayor Giuliani will make his pitch tomorrow to Christian conservatives, aiming to convince them that his bona fides on leadership and fiscal discipline should trump his views on social issues like abortion.

Mr. Giuliani is speaking at Regent University, the Christian school founded by the prominent evangelist, Pat Robertson. But rather than focusing on his support for abortion rights and gay rights, which could meet with a chilly reception, the former mayor is expected to play it safe. A campaign spokeswoman, Maria Comella, said he is likely to discuss his proposals to cut taxes and reduce wasteful government spending, which he detailed in a policy speech in Iowa last week.

That would not surprise the dean of Regent’s Robertson School of Government, Charles Dunn, who predicted Mr. Giuliani would steer away from the hot-button social topics. “I expect him to stick with his game plan, to stay with what got him here,” Mr. Dunn said. “I doubt he will say much of anything about his social views.”

While that might disappoint some of the more than 600 people who bought tickets to the luncheon speech, Mr. Dunn said, it could be a smart move for a candidate whose message to conservatives has been that he, more than his rivals, is the one who can win a general election and keep the White House in Republican hands.

Mr. Giuliani has maintained his lead in many national polls, but the rise of a former Massachusetts governor, Mitt Romney, and the likely candidacy of a former Tennessee senator, Fred Thompson, have cut into his support in early voting states such as Iowa and South Carolina, where social conservatives heavily influence the Republican primaries.

Regent University has been a popular stop for Democrats and Republicans. Mr. Romney delivered the commencement address there last month, while Vice President Gore and a 2004 Democratic presidential contender, General Wesley Clark, have spoken at the university in past years.

Mr. Giuliani’s appearance at the college, however, has been the most anticipated of any, Mr. Dunn said. The event has sold out, and the university is expected to set up an overflow room to broadcast his speech. Mr. Giuliani was originally scheduled to speak at Regent on April 17, but his campaign canceled that appearance following the Virginia Tech shootings, which occurred the day before.

Since that time, Mr. Giuliani has made a concerted effort to clarify his stance on abortion, following shaky responses to questions on the issue during the first Republican debate last month.

During one exchange, he said it would be “okay” if the Supreme Court overturned the Roe v. Wade decision. In a series of interviews and speeches during the subsequent week, he elaborated on his position and stated that while he personally “hates” abortion, he supports the right of choice for women. He has also repeatedly stated that while he was mayor of New York City, abortions dropped and adoptions rose, and he has made one of his “12 commitments” to replicate that nationally.

Although Mr. Giuliani has stopped getting questioned on abortion at every campaign appearance, his newly sharpened approach has not won over staunch foes of the practice. “I don’t think he’s going to get the pro-life vote,” the legislative director for the National Right to Life Committee, Darla St. Martin, said, calling his position “extreme.”

“Pro-lifers want a pro-life candidate,” she said.

Mr. Dunn of Regent takes a different view. He argues that many evangelical Christians have not sworn off Mr. Giuliani by any means.

He divides them into two groups: There are “purists,” like a leader of the Southern Baptist Convention, Richard Land, and the founder of Focus on the Family, James Dobson, both of whom have said they could not vote for Mr. Giuliani even if he was the Republican nominee. And then there are “pragmatists,” Mr. Dunn said, who are open to supporting the former mayor if they believe he has the best chance of winning next November.

At tomorrow ‘s address, Mr. Dunn said, both groups will be listening. “This speech is really very important for him to try to appeal to the pragmatists and to continue to try to build a bridge to the purists,” Mr. Dunn said.