The head of the City Council’s Bronx delegation, Madeline Provenzano, quietly stepped down from that leadership post late last month – the same week she said she would support Mayor Bloomberg for re-election. She told The New York Sun in an interview Friday that the decision was hers and she was not pushed out.

Ms. Provenzano, a Democrat who has supported the Republican mayor on his opposition to increasing public campaign-matching funds and has sided with her more moderate colleagues in the council on other issues, said she simply decided it was time to pass the torch.

“I only have one year left in the council,” she said. Ms. Provenzano, who represents Morris Park and Pelham Parkway, will be forced from her seat in November by term limits.

“I just thought it would be wise to get someone else in so that I could help them transition to the job,” she said.

During an informal meeting at City Hall, the eight-member delegation voted unanimously to install Council Member Maria Baez, a first-term Democrat, as the borough’s new leader. Ms. Baez was the only member of the delegation to seek the position.

The leadership change was made without fanfare. It was, however, the first borough leadership shakeup since December 2003, when the council’s Brooklyn delegation ousted its leader, Lewis Fidler, and replaced him with Bill de Blasio and Albert Vann, who now share the post.

That coup is still cited in Brooklyn political circles and will probably be more widely invoked when the council speaker, Gifford Miller, vacates his seat at the end of this year and the race to replace him heats up.

All three of those council members from Brooklyn are interested in the speakership post.

Though leading a borough delegation does not come with public glory, a delegation head works closely with the speaker’s office to craft spending priorities during budget negotiations. The job is not considered an official government position and comes with no stipend or staff.

The council’s majority leader, Joel Rivera, said yesterday, “Nobody would have even thought of this if Madeline hadn’t brought it up.” Ms. Provenzano, he said, has been an asset to the Bronx delegation, partly because of her close relationship with the Bloomberg administration.

“It’s not a rah-rah position, but it’s very important because you have responsibility in budget negotiations and you sit on the steering committee,” Mr. Rivera said. “Madeline told me she wanted to concentrate on her district and help with the transition.”

Mr. Rivera also stressed that the speaker, who plans to seek the Democratic nomination against Mr. Bloomberg this year, has no control over who heads each borough’s delegation. Still, Ms. Provenzano is one of several conservative Democrats in the council expected to endorse Mr. Bloomberg in November’s election over Mr. Miller or another Democrat.

Last month she told the Sun: “They haven’t asked me to make a formal endorsement yet, but when they do, I’ll be there. I supported Mayor Bloomberg the first time because I didn’t think he’d be beholden to anyone. Now I am supporting him because he’s shown he has the right stuff. He needs another term to finish what he has started.”

With a 5-to-1 ratio of Democrats to Republicans among enrolled voters in the city, support from moderate Democrats is crucial for the mayor’s re-election.