Mayor Anthony A. Williams said the D.C. government subsidy for a baseball stadium could run as high as $300 million but pledged that nearly all of the cost would be covered by revenue generated at or near a new ballpark.

Williams, who two years ago set the ceiling for a subsidy at $200 million, also committed himself to an ambitious timetable, promising to select one of five stadium sites and assemble a financing package by the end of February.

His comments, made in an interview late Friday, came in response to Major League Baseball's renewed urgency in relocating the ailing Montreal Expos for the 2004 season. Baseball officials, who privately have expressed skepticism about the firmness of Washington's bid, plan to formally meet with representatives of the city and several other interested areas, including Portland, Ore., and Northern Virginia, early next year.

"I know that it's been wait, wait, wait, wait," Williams said. "Now we have to speed up everything dramatically . . . and that's what we're ready to do."

Williams has made returning baseball to Washington a priority of his second term in office, which begins Jan. 2. And though baseball officials have publicly indicated that the Washington area is among the nation's most attractive potential markets, major obstacles remain to landing a team, including the vehement opposition of Baltimore Orioles owner Peter G. Angelos.

The most important factor in improving Washington's bid will be its ability to put together a stadium deal that's financially and politically viable while the city faces serious fiscal troubles, say government and baseball officials.

The mayor's suggestion that a city government financing package might reach $300 million surprised members of the D.C. Council who had been working under the assumption that the limit was $200 million. That's the amount Williams pledged in a letter to baseball officials in November 2000.

A consultant's report paid for by city officials and a potential ownership group last month listed five possible sites and suggested financing options, including dedicating taxes collected at the ballpark and in a nearby development zone toward repaying a construction loan. The report put the cost of a stadium at $342 million to $542 million, depending on its location.

Three of the suggested sites are near downtown: east Mount Vernon Square, the new Metro stop under construction at New York Avenue and a site near Union Station, just north of Massachusetts Avenue. A fourth possible location is on the Anacostia River waterfront, near South Capitol Street. The fifth is just north of the existing Robert F. Kennedy Memorial Stadium in Northeast Washington.

City lawmakers are extremely reluctant to use any of the city's existing sources of revenue for a stadium, a move that would open them to criticism that the money could be better spent on improving the city's schools, health care or other social services.

"I'm not sure you can get to $200 million, much less $300 million," said Council member Jack Evans (D-Ward 2), chairman of the finance and revenue committee. "I don't see any chance that any existing revenue stream would be used for a baseball stadium."

The mayor went nearly as far Friday, saying the "overwhelming amount of your finance dollars" would come from sources directly tied to a ballpark. "We're willing to go as far as we can without actually tapping into the existing budget of the city."

Williams has said that a financing package could include land, road improvements and new borrowing by the city government, with the revenue to be repaid by dedicated taxes.

Council member Sharon Ambrose (D-Ward 6), a skeptic on major public financing for a stadium, said she wants to know much more about the mayor's proposed package.

"I don't know how he put that number together," she said. "We also don't know how we're going to fund the operations of the District government, so I don't know what he's talking about."

The city hopes to tax the income of baseball players who would play at a new stadium, as does nearly every state that hosts Major League teams. Williams said he will seek approval for such a tax from Congress, but the effort is complicated by the long-standing prohibition against the city taxing dollars earned within its borders by nonresidents. Such a tax could earn more than $7 million a year on an average baseball team payroll of $80 million.

Baseball executives, speaking on the condition of anonymity, question whether the city can pay its share for a ballpark. Local baseball boosters also believe city officials should have been more aggressive in picking a stadium site and detailing a finance package in the month since the consultant's report was issued. Plans for moving the Expos have developed quickly since the league settled its labor problems in August. League officials say they want a decision on relocation before the All-Star Game in July.

Opponents of public funding for a baseball stadium say that however creative the financing deal, it still will drain away tax dollars that could be used for other purposes.

"We'll never be able to pay for our schools and our health care if we keep cutting the tax base. It's insane," said Debby Hanrahan, a member of the D.C. Statehood Green Party. "It's not helping the city at all financially."