The man once dubbed "America's mayor" has taken the first step toward becoming America's next president. Former New York City Mayor Rudy Giuliani, a Republican moderate who achieved near-mythic popularity for his handling of the Sept. 11 attacks, filed papers Friday in New York to create the Rudy Giuliani Presidential Exploratory Committee Inc. A copy of the document was obtained by The Associated Press. Creating an exploratory committee does not make Giuliani a declared candidate, but it does mean he intends to travel the country gauging support and preparing for a White House bid. "Mayor Giuliani has not made a decision yet," Giuliani spokeswoman Sunny Mindel said in a statement Monday night. "With the filing of this document, we have taken the necessary legal steps so an organization can be put in place and money can be raised to explore a possible presidential run in 2008." One potential rival for the GOP nomination, Sen. John McCain (news, bio, voting record) of Arizona, said Sunday he was taking the initial step of setting up an exploratory committee. Under federal election law, an exploratory committee allows an individual to travel and gauge the level of support for a candidacy without formally declaring themselves a candidate and adhering to all the federal rules of fundraising. An individual who spends money only to test the waters - but not to campaign for office - does not have to register as a candidate under the election law. The GOP field is expected to grow with other presidential hopefuls, among them Massachusetts Gov. Mitt Romney, Sen. Bill Frist (news, bio, voting record) of Tennessee, Arkansas Gov. Mike Huckabee and New York Gov. George Pataki. Democratic Gov. Tom Vilsack of Iowa has filed to establish a full-blown campaign committee and will make a more formal announcement of his candidacy later this month. Giuliani has said for months that he would wait until after the 2006 elections to decide whether to embark on a White House bid. The former mayor is a moderate who supports gun control, same-sex civil unions, embryonic stem-cell research and abortion rights - stands that would put him at odds with the majority of the GOP conservative base. In 2006, the Giuliani brand remained strong. He headlined fundraisers for Republican candidates nationwide, and his travel has done little to deny 2008 ambitions. Giuliani enjoys strong name recognition. An AP-AOL News poll conducted in late October found that, among Republicans, Giuliani was essentially tied with Secretary of State Condoleezza Rice and McCain as the person they would most like to see elected president in 2008. Rice has insisted that she will not run. Giuliani was in his final months as New York City mayor when a pair of planes crashed into the World Trade Center's towers. Within hours, he was visiting the site, caked in dust and walking through the chaos, a moment replayed repeatedly on television. Assuming the role of "America's Mayor" and Time magazine's Person of the Year for 2001, Giuliani remained an in-demand speaker and GOP fundraiser. He was the first Republican to lead New York City in decades, cut crime and redeveloped rundown parts of the city. He was a former US attorney, leading campaigns against organized crime and corruption. He spent two years as the Justice Department's No. 3 post, overseeing all US attorneys, the Drug Enforcement Agency and the US Marshals Service. The Brooklyn native was first elected New York's mayor in 1993. Prior to Sept. 11, Giuliani also his share of critics, many of whom argued that the city's falling crime rate was partly due to an overly aggressive police force that too often used excessive or deadly force. Giuliani eyed a run for the Senate in 2000, but he ended that bid while battling prostate cancer and a made-for-tabloids divorce from television star Donna Hanover. The messy divorce and his relationship with Judith Nathan made a campaign against Hillary Rodham Clinton all the more difficult.