One of the best-known members of the City Council, Eva Moskowitz, officially entered the crowded Democratic race for Manhattan borough president yesterday as she announced her candidacy on the steps of City Hall surrounded by more than 200 supporters, including public-school children and her third-grade teacher.

Meanwhile, a council member from Brooklyn, Charles Barron, finally made official what had been suspected all along and dropped out of the race for mayor to run for re-election. The East New York council member pledged his support to the current Manhattan borough president, C. Virginia Fields, as she continues on in the citywide race.

With nine Democratic contenders vying to succeed Ms. Fields, who is prevented by term limits from seeking reelection, Ms. Moskowitz has emerged as the leader in fund-raising. She reports having raised $905,683 so far, compared to $762,179 for the candidate with the next highest total, Assemblyman Scott Stringer. Most of the remaining candidates have raised barely $200,000.

Ms. Moskowitz, who serves as chair woman of the council’s Committee of Education, has built support from many public-school parents and educators. She told the crowd gathered with her, clad in red hats emblazoned with her first name, that she would be “a relentless advocate for people of this great borough.”

Ms. Moskowitz said she arrived at the council in 1999 “with a baby in one arm and a copy of the City Charter in the other.”

“Six years, 80 education committee hearings, 10 laws, and two more kids later, I am ready to do more,” she said.

“Some have said that I am too tough, too demanding, too overzealous,” Ms. Moskowitz said. “But no parent has ever said I have fought too hard to get their child out of a failing school. No tenant has ever complained that I worked too hard to get their heat and hot water back on. No taxpayer has ever complained that I fought too hard against government waste and in efficiency.”

She pledged to expand “affordable housing” and to oppose the West Side Stadium, which she said “puts the needs of sports teams ahead of working families.”

Ms. Moskowitz, who represents the East Side, would not have to vacate her council seat until 2009.

As the race for borough president heats up, the Stringer camp sent an email out over the weekend announcing the kickoff for his campaign on March 10. Mr. Stringer represents the Upper West Side and Clinton.

The office of borough president is seen as largely ceremonial, particularly now that the Board of Estimate no longer exists, but David Dinkins and Robert F. Wagner used the position as a stepping-stone to the mayor’s office.

Ms. Moskowitz has said she wants to be mayor someday. Ms. Fields’ hopes of winning what is now a four-candidate Democratic primary got a boost with Mr. Barron’s endorsement. In a press conference at the steps of City Hall, Mr. Barron made the announcement and introduced Operation POWER, People Organizing and Working for Empowerment and Respect, a political movement that aims to increase accountability of elected officials.

Mr. Barron, who is black, has said that running against Ms. Fields, who is also black, would cause them to “cancel each other out.” He said that if he couldn’t win the mayoral race, he would focus on developing his grass-roots movement to support a candidate who could.

“We want to unite everybody,” Mr. Barron said. “We would be too divisive if I stayed in,” he said.