Mayor Bloomberg claims he’s not running for president when his time at City Hall is up, but he is taking a high profile role on several national issues.

Mr. Bloomberg showed a rarely seen conservative side this week when he denied his aides’ recommendation to request a federal waiver to expand the city’s food stamp program. Yesterday, Mr. Bloomberg returned to a more typical liberal stance when he announced plans to host an anti-gun summit with mayors from around the nation.

Political observers say the two positions are not inconsistent and make Mr. Bloomberg an ideal third-party candidate if he decides to run for higher office.

“Bloomberg’s political persona is part liberal, part moderate conservative,” a University of Virginia political scientist, Larry Sabato, said. “He’s being mentioned as a possible centrist candidate for president, so it fits in that mold. Any independent candidate is going to have some positions that are more liberal and some that are more conservative.”

The renewal of his war on guns was welcomed by gun control supporters, who already have lauded him for taking on his Republican brethren and making the issue central to his second term agenda. Less than 24 hours earlier, advocates for the poor criticized him for opting against a federal waiver that would have loosened eligibility for some adults seeking food stamps. They characterized the move as a setback that was reminiscent of Mayor Giuliani’s high-profile crackdown on the welfare rolls. Fiscal conservatives applauded it and said it would help push more adults toward self-sufficiency.

“I’m a believer that people should have to work for a living,” Mr. Bloomberg told reporters yesterday after an announcement at Elmhurst Hospital in Queens. “You have to have a penalty if there is a requirement to work, and this penalty is one that’s appropriate,” he said. “Remember … the city has a whole host of programs to make sure that nobody goes without food.”

“On the one hand, he’s throwing a bone to liberals who care about gun control,” a professor of government at Dartmouth College, Linda Fowler, said, “and on the other, he’s preserving his reputation as being tightfisted with the taxpayers’ money.”

Ms. Fowler said she did not believe a New York Republican could make a successful run on a national platform, but that Mr. Bloomberg’s recent position “certainly doesn’t hurt if he were to have aspirations for statewide office” like governor or senator.

The National Summit on Illegal Guns that the mayor is co-hosting at Gracie Mansion next week with the mayor of Boston, Thomas Menino, will bring together mayors from a dozen cities, including Dallas, Milwaukee, Philadelphia, and Trenton, N.J. Mr. Bloomberg said the mayors of Los Angeles, Chicago, and other large cities were invited but could not come because of scheduling conflicts. He said the issue was not a question of ideologies.

“Combating gun violence is not a partisan issue,” the mayor said in a statement. “Illegal guns are hurting innocent people across America, whether you are east or west of the Mississippi or north or south of the Mason Dixon line.”

Mr. Bloomberg is pursuing a lawsuit against several gun manufacturers that he said too easily allow criminals to get their hands on guns and traffic them between states. Last month he testified against a bill in Washington that would limit access to a gun database for civil lawsuits. Still, Mr. Bloomberg and his fellow mayors are up against federal legislation that largely protects gun manufacturers from liability.

Ms. Fowler said mayors from the nation’s largest cities would have a better chance as a coordinated coalition than as individuals and that it made sense for Mr. Bloomberg to spearhead the effort.

“Mayors of New York City have always liked to think of themselves as leaders among mayors,” she said.