Miller (D-Manhattan), a likely mayoral contender in 2005, and Campaign Finance Board chairman Frederick A.O. Schwarz, whom Bloomberg appointed to succeed longtime board chairman Rev. Joseph O'Hare, are distant relatives.

The board earlier this week unveiled a proposal to greatly increase the amount of public funds available for the campaigns of Miller and other potential Bloomberg challengers, infuriating the mayor, who said he was blindsided by the plan.

Bloomberg earlier ripped Miller for trying to gain an unfair advantage over other candidates and yesterday the mayor turned his guns on the Campaign Finance Board.

"That's not the kind of democracy and [above-board] politics that this organization is supposed to have, and it certainly would never have done that under the predecessor, Father O'Hare," Bloomberg said on his weekly WABC radio show.

"He was scrupulously honest. A lot of mayors disliked what he did, but nobody ever questioned his integrity or the process where he made sure that it was not part of some politician trying to feather their own nest," Bloomberg added.

The board's proposals would increase public matching funds by up to 8 to 1 for candidates running against opponents who refuse to abide by spending caps, like the billionaire Bloomberg.

"The issue here is not whether you agree or disagree; the issue is that it was a backroom deal," the mayor said. Schwarz told The Post that the accusation of a secret deal "doesn't wash" and all sides have been talking since last summer.

"When you combine the number of meetings and phone calls, we had more meetings with the [Bloomberg] corporation counsel than with the City Council," he insisted. He said Bloomberg's chief counsel, Michael Cardozo, was "very helpful" on the bill.

Bloomberg, who spent $75 million of his own money on his 2001 campaign, pointed out that other board members were kept in the dark.

"I'm still waiting for an explanation," the mayor said.

Schwarz said the announcement was accelerated by The Post's reporting of the story on Tuesday and that all his colleagues knew the details. Attempts to reach O'Hare were unsuccessful.

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City Council Speaker Gifford Miller will endorse Howard Dean for president on Monday, The Post has learned.

Miller had been thinking of backing Gen. Wesley Clark before settling on Dean, the Democratic front-runner.

Miller's backing will be announced on the same day that Dean holds several fund-raisers in the city, concluding with a $1,000-a-head "roast" hosted by Hollywood honcho Rob Reiner. The bashes could take in $1 million or more.

Miller (D-Manhattan) will join City Council members Bill Perkins, Eric Gioia and David Yassky in backing Dean.

Sen. Joe Lieberman was endorsed by state Sen. Ruben Diaz and Assembly member Carmen Arroyo.

- Stefan C. Friedman