IT LOOKS LIKE the race for mayor of Boston is off to a testy start.

City Councilor Michelle Wu called Mayor Marty Walsh as a courtesy on Sunday to tell him that she plans to run for mayor. Most politicians, when they get such a call, say thanks and start preparing for the fight ahead.

But Walsh on Monday told a Boston Globe reporter what Wu had told him, effectively making her campaign announcement for her. Miffed, Wu declined to confirm her campaign plans after Walsh’s disclosure.

At a press conference outside City Hall on Tuesday, Walsh acted as if he had no choice but to announce Wu’s coming candidacy.

“A reporter from the Globe asked me the question. He had heard that I had a call from the councilor and I just confirmed I did,” Walsh said.

Asked why he didn’t just say no comment to the reporter, Walsh said he didn’t feel comfortable doing that. “When I say no comment to you guys and I know the answer, it’s not fair to do,” he said.

Michael Goldman, who served as a consultant to Walsh’s 2013 campaign, said the Globe reporter called Walsh at home and Walsh confirmed what the reporter had been hearing. Goldman stressed that the Globe reporter contacted the mayor and the mayor was only confirming what the reporter was hearing. “There was no plan to do it,” Goldman said.