The mayor, who has said his endorsement is up for grabs in the presidential race, made a similar introduction two weeks ago, when he spoke before a speech by Democratic candidate Sen. Barack Obama, of Illinois.
Bloomberg had considered his own independent presidential campaign but said in February that he had decided not to run. His focus, he said at the time, would be on getting the candidates to embrace a bipartisan approach.
He said then that he might endorse a candidate who does not work along party lines, addresses the intricacies of issues and has thought ahead to the legislative process and how to finance specific programs. He said he wants to see them "coming up with things that make some sense to me."
Bloomberg, a Democrat-turned-Republican-turned-independent, has long-standing ties to McCain. In 2001, when Bloomberg was a politically untested businessman attempting a long-shot bid for City Hall, McCain endorsed the then little-known Republican.
The mayor also has worked closely with Obama's Democratic rival, New York Sen. Hillary Clinton.
