Toronto Mayor David Miller said Thursday he will support Adam Giambrone and will not call for him to step down as chair of the TTC.

Adam Giambrone has now admitted to 'multiple' affairs with women other than his partner. (CBC)

On Wednesday, Giambrone pulled out of the race to replace Miller, after he admitted that he had had inappropriate relationships with women and lied about it in the media.

Miller said he has absolute confidence in Giambrone "because he is doing a terrific job."

"I'm going to stand by him as chair of the TTC," Miller told a news conference.

The mayor said it was "unfortunate" that Giambrone had to drop out of the campaign. "I thought he had tremendous potential." he said.

Service and ridership have improved markedly in recent years, he said.

"There's a renaissance in public transit in Toronto," Miller said, adding the media should focus on Giambrone's record as chair.

"Pierre Trudeau once said: 'The government has no business in the bedrooms of the nation.' I think, frankly, there are areas where the media has no business as well," Miller said.

"Adam Giambrone has stood before the people of Toronto. He has accepted responsibility for his actions. He is working with his partner on his private life."

Board member calls for resignation

Shortly after Miller's comments, a councillor who sits on the TTC board argued Giambrone was no longer fit to stay on as chair.

Peter Milczyn told CBC News it already appears Giambrone will miss a key meeting on Friday — an update on a proposed blue-ribbon panel that is to review customer service at the transit agency.

"He's needed here but if he's too busy trying to sort out his personal relationships, then he should step down," said Milczyn.

"If Mr.. Giambrone voluntarily steps down, I think that will be a good thing for him and a good thing for the TTC at this point."

After Friday's meeting, the TTC board will meet again next Wednesday. A motion calling for Giambrone's resignation can be presented at that meeting. The motion would need six votes from the nine-member commission just to be considered.

It doesn't immediately appear that anyone on the TTC board will put forward such a motion.

Top mayoral candidate George Smitherman has also called on Giambrone to step down, saying that the transit commission needed a leader who was "100 per cent focused" on improving service.