Despite documented differences of opinion on major policy platforms, the speaker of the state Assembly, Sheldon Silver, threw his support yesterday behind the Democratic mayoral front-runner, Fernando Ferrer, in an endorsement expected since mid-July.

Mr. Silver’s pledge of support was issued above the din of Chinatown’s sidewalks at a press conference in front of the Tai Hong Lau Restaurant on Mott Street. Flanked by a phalanx of Asian-American elected officials – including Assemblyman Jimmy Meng, a Democrat of Queens, who has endorsed Mr. Ferrer – Mr. Silver, a Democrat who represents Lower Manhattan, praised the former Bronx borough president’s record on education and “affordable housing” and said the candidate “should be and can be the most effective mayor of the city of New York.”

In the 2001 mayoral race, Mr. Silver endorsed one of Mr. Ferrer’s opponents in the Democratic primary, the former city comptroller, Alan Hevesi. In April, Mr. Silver said Mr. Ferrer’s campaign was in a “freefall” after the candidate’s now-infamous remarks about the police shooting of Amadou Diallo, which sent his poll numbers plummeting and threatened to derail Mr. Ferrer’s campaign. Mr. Silver said yesterday that he was now endorsing Mr. Ferrer because it was clear the Diallo episode was “isolated.” Mr. Ferrer’s poll numbers have been rebounding.

The expression of support from the Assembly speaker came in spite of marked differences of opinion on one of Mr. Ferrer’s most visible policy platforms, his proposed reinstitution of a stock-transfer tax on Wall Street to generate $1 billion a year for city schools. Mr. Silver – who, when blocking Mayor Bloomberg’s efforts to build a stadium on the West Side of Manhattan, said he was prioritizing the rehabilitation of his Assembly district – denounced Mr. Ferrer’s plan in April, saying it would harm the area’s economy.

When asked about the disagreement at yesterday’s press conference, Mr. Silver said he hoped to persuade Mr. Ferrer to abandon the proposal. Mr. Silver was also asked yesterday about the commuter tax, eliminated in 2001. Mr. Silver endorsed the repeal and remained in favor of the tax’s elimination yesterday, while Mr. Ferrer has favored the tax and in 1999 called its repeal “a cynical act.”

During a question session with reporters, Mr. Ferrer was also asked about comments made earlier in the day by Mr. Bloomberg during a press conference at Coney Island in Brooklyn. The mayor, defending himself against Mr. Ferrer’s criticism Monday of his record on subway security, said: “This is someone who said the first thing he would do is fire Ray Kelly.”

Mr. Ferrer retorted that Mr. Bloomberg was confusing him with another Democratic contender, the Manhattan borough president, C. Virginia Fields, who promised to terminate Mr. Kelly if she acceded to the mayoralty.