If Mayor Giuliani’s presidential run takes off, it could mean the end of his lucrative international consulting business, Giuliani Security & Safety, set up to advise clients on combating terrorism.

“The reason people pay a lot of money for this type of consulting is because you have a big name associated with it,” a fellow at the Integrated Center of Homeland Security at Texas A&M University, William Hancock, said.

Mr. Hancock said the company, which is part of the larger Giuliani and Partners, could see a big drop-off in business without Mr. Giuliani at the helm.

This week, Mr. Giuliani set up a nonprofit with the state of New York, the Rudy Giuliani Presidential Exploratory Committee, to explore whether there is enough support for him to make a full-blown attempt at the White House. He has gathered a band of longtime political loyalists, including Dennison Young, Peter Powers, and John Gross, along with some players from national Republican circles.

Anne Dickerson, who helped head up President Bush’s fund-raising efforts in 2004, is building Mr. Giuliani’s war chest. Christopher Henick, who joined Giuliani Partners in 2003 and was previously a deputy assistant to Karl Rove, is also in place. And Jacob Menges, the political director of Mr. Giuliani’s political action committee, Solutions America, has also signed on.

Although Mr. Giuliani’s spokeswoman, Sunny Mindel, said no fundraising events have been scheduled, money is not likely to be a problem.

Mr. Giuliani collected a wealth of political chits this year, as Solutions America donated $230,000 to 55 candidates across the country, all Republicans. The former mayor also crisscrossed the nation campaigning for candidates. Although a number of them lost on Election Day, many winners are ready to return the favor.

As Mr. Giuliani begins calling in favors, it appears support for his candidacy is growing.

Among the potential backers is Lieutenant Governor Michael Steele of Maryland, whom Mr. Giuliani campaigned for in both 2002 and 2006 and who lost his Senate bid last week. Mr. Steele said he “gets a tickle out of calling him America’s mayor” and told The New York Sun,”I would be open to helping with fund-raising and absolutely want to help him.”

Mr. Steele said he is looking forward to sitting down with Mr. Giuliani and “hearing his vision for America.” He added, however, that he is also looking forward to hearing from Senator McCain, a Republican of Arizona who is also expected to launch a presidential bid.