“I said exactly what I wanted to say. I conveyed exactly the message I wanted to convey.”

Only the previous week, Mr. Giuliani veered off topic at a realtors’ conference in Las Vegas to assail the president’s irresolute stance toward President Bashar al-Assad of Syria, attendees said. And on Feb. 13, he told an Iranian-American group in Arizona that Mr. Obama was not “a man who loves his people.” (In an online video of the event, Mr. Giuliani is shown shouting: “Mr. President, wake up. Come off the golf course.”)

Mr. Giuliani’s friends and political associates say he has become a man obsessed — horrified at what he views as a listless White House approach to terrorism and instability in the Middle East, and eager to say so…

Mr. Giuliani has plainly not mellowed in his prosperity. Representative Peter T. King, a Long Island Republican who has known him for decades, said the former mayor was “very personally angry” in his remarks, on and off the stage at the fund-raising event on Wednesday evening.

“This is as emotional as I’ve seen him. He was in some ways more emotional than he was after 9/11,” said Mr. King, who spoke alongside Mr. Giuliani at a private “super PAC” fund-raising event at the Women’s National Republican Club in Manhattan.