The speaker of the City Council, Gifford Miller, is celebrating his 35th birthday in much the same way he celebrated his 34th last year: soliciting donations for his mayoral campaign.

Mr. Miller is holding a birthday fund-raising party tonight at the Ritz Carlton in Battery Park, where he is expected to raise about $500,000. The event, sources said, is expected to draw about 300 to 500 guests, with a minimum donation of $2,000 for the VIP cocktail hour and $250 for the main reception.

Though the speaker is not considered the frontrunner among the half dozen prominent Democratic potential candidates, he has been leading in fund-raising. In the most recent filing with the city’s Campaign Finance Board in July, Mr. Miller reported raising $3.3 million. The city comptroller, William Thompson Jr., was second with $2.7 million, and the former borough president of the Bronx, Fernando Ferrer, ranked third with $1.3 million.

Mr. Ferrer, who finished first in the 2001 Democratic mayoral primary but lost to Mark Green in the runoff, is the only Democrat who has consistently polled better than Mayor Bloomberg. In a Quinnipiac University poll earlier this month, he was preferred by 45% of respondents, to Mr. Bloomberg’s 40%.

Mr. Miller’s birthday bash comes in the thick of his fight with the mayor over changing the city’s program of public financing for campaigns. In late October, the City Council voted to raise the limit on public matching funds to $6 for every $1 privately raised, from the current cap of $5. Under the legislation, candidates facing opponents who opt out of the public system and spend three times the legal limit would be eligible for the $6 rate. In the mayoral race, for example, candidates such as Mr. Miller or other Democratic contenders would get the top rate if they faced someone who spent $17.1 million or more. Mr. Bloomberg, a billionaire, has said he spent more than $70 million in connection with the 2001 primary and election.

Last week, after weeks of public denunciations of the bills, Mr. Bloomberg vetoed the matching-fund hike and two companion pieces of legislation. The mayor also proposed his own legislation, which would limit contributions from individuals who do business with the city to $250 and would eliminate matching fund eligibility for those donations. The contributions are crucial to many elected officials, including Mr. Miller.

Mr. Miller, who is being forced out of his council seat by term limits, has been aggressively raising money for a 2005 election for the last several years. For his birthday last year, he held a party at a Midtown nightclub that raised roughly $500,000.

A political science professor at Baruch College, Douglas Muzzio, said yesterday that a birthday event, highlighting that the speaker is only 35,could be tricky as Mr. Miller tries to counter some adverse impressions created by his age and youthful appearance. But Mr. Muzzio called Mr. Miller a “tireless worker,” a “prodigious fund-raiser,” and a “savvy campaign strategist.”