Alyssa Cwanger, Post-Gazette Sen. Rick Santorum, left, and Rudolph W. Giuliani walk down the red carpet before the All-Star Game. Click photo for larger image.

A lot of stars crossed the Roberto Clemente Bridge on Tuesday night, but few drew a warmer reception than the bald guy in the Yankees cap.

Chants of "Rudy, Rudy Rudy" met him as he walked with U.S. Sen. Rick Santorum, R-Pa., moments before the first pitch of the All-Star Game.

"Rudy's in the house," one clearly delighted fan yelled.

"Giuliani for president," screamed another.

More people could be mouthing that slogan, and doing it more seriously, if the former New York City mayor, Rudolph W. Guiliani, decides to seek the GOP nomination in 2008.

Mr. Giuliani has acknowledged that he may enter the wide-open GOP contest, but he has declined to offer a timetable for his deliberations.

"Not tonight," was all he would say Tuesday when asked when he might announce a decision.

The Giuliani speculation is inevitable. He forged a strong, if prickly, reputation as a big city mayor who largely succeeded in the daunting task of driving down crime and restoring livability to New York City. His image leapt to a new level with the steady, reassuring manner he projected amid the horror of the Sept. 11, 2001, terrorist attacks.

But on another level, his potential candidacy strains political plausibility. The voters who will choose the Republicans' next nominee don't fit the profile of the fans outside PNC Park. Mr. Giuliani is a liberal, big city Northeasterner hoping to seize the reins of a conservative party dominated for decades by the South and the West.

In early polling on the Republican race, however, the former mayor's numbers look formidable. Mr. Giuliani led the field in a Gallup poll last month with the support of 29 percent of Republican voters. Sen. John McCain of Arizona was second with 24 percent and no other Republican contender managed double digits. Mr. McCain edged the former mayor in some other recent national polls, but no other candidate was close to the leading pair in any of those surveys.

First choice in Pa.

In Pennsylvania, where Mr. Giuliani made appearances for both Mr. Santorum and Republican gubernatorial contender Lynn Swann last week, the story is much the same. A survey last month by the Republican consulting firm Strategic Vision found Mr. Giuliani to be the first choice of 39 percent of likely Republican voters, while Mr. McCain was the choice of 28 percent and the next strongest presidential hopefuls, former House Speaker Newt Gingrich and Massachusetts Gov. Mitt Romney, tied at 5 percent.

Polling experts caution that horse race numbers for a competition as far off as the 2008 presidential race are a better measure of raw name recognition than committed support. Name recognition, nonetheless, is a valuable asset on its own and an important foundation for the fund-raising challenge that faces any presidential aspirant.

Mr. Giuliani has proved a fund-raising draw for GOP candidates across the country, including, notably, in a stop last month in Iowa, the traditional site of the first presidential contest of the nominating season. In addition to his Pennsylvania stops, he made appearances last week for GOP candidates in Illinois and Ohio.

In speculation about the 2008 battle, however, those signs of political strength for Mr. Giuliani collide with the conventional wisdom that his positions on social issues are at odds with the hard-core Republican cadres who will decide the nomination.

Mr. Giuliani is pro-choice on abortion, favors gay rights and domestic-partner benefits, and was a strong voice for gun control as mayor, all problematic positions in a fundamentally conservative party.

Dennis Goldford, a professor of political science at Drake University, said such a position would be a tough sell to the Christian conservatives who are a dominant influence in the labor-intensive Iowa caucuses, the starting blocks of the presidential race.

"He's got a reputation for leadership," he said of the ex-mayor, "but I think he would have a difficult time. He would raise real concerns among the religious conservatives that are so strong in the party out here."

Mr. Goldford said a Giuliani candidacy would buck not only an Iowa, but also a national tide in Republican politics. He noted that 13 of 14 Republican nominees for president since 1952 had been from west of the Mississippi.

"The whole point of the conservative insurgency and takeover of the Republican Party was to take control of the party from the old-line Easterners," he said.

As he stood by the Allegheny River, awaiting Mr. Giuliani's arrival Tuesday night, U.S. Sen. John Ensign, R-Nev., called the ex-mayor "a great leader," but enumerated some of the hurdles he faces on the way to the GOP nomination.

"It would be difficult, no question," Mr. Ensign said of Mr. Giuliani's chances for the nomination. "And I'll tell you what the toughest issue is. It's not abortion, and it's not the gay issue. It's the gun issue. In the West, and I'm from Nevada, you don't touch people's guns. I think that's going to be a very difficult issue to overcome. We'll see. Does he moderate his position on that?"

In addition to Mr. Giuliani's ideological heterodoxy, some conservatives might be put off by his very public personal upheavals, such as the divorce from former Pittsburgh television personality Donna Hanover, which provided sensational fodder for his city's tabloids for months.

As if to rebut the questioning of his conservative credentials, the home page of Mr. Giuliani's Web site, www.solutionsamerica.org, showcased a 1998 George Will column headlined, "Rudy: America's Most Successful Conservative.''

His collection of political chits from conservative Republicans such as Mr. Santorum also can be viewed as efforts to buttress his ideological bona fides.

And returning the ex-mayor's support, Mr. Santorum said Mr. Giuliani could, indeed, be a formidable contender in the GOP presidential competition.

The issues that are first and foremost on the minds of the American public right now [involve] national security," Mr. Santorum said. "And, you know, he's got a very solid record as someone who's been an inspirational leader in difficult times, and this is a difficult time."