Opponents of a publicly funded D.C. baseball stadium conceded yesterday that they are unlikely to stop the project, while aides to Mayor Anthony A. Williams said they are developing detailed plans to show how tax revenue generated by the ballpark could help schools, libraries and recreation centers.

As an Oct. 28 public hearing before the D.C. Council approaches, both sides are scrambling to make their cases and solidify support, even with Williams (D) and five council members on an 11-day tour of Asia.

Although critics of the mayor's $440 million stadium financing package said they still intend to try to block the use of public funds for the project, they acknowledge that the battle in the end may not be over stopping the plan but amending it to ensure economic benefits to city neighborhoods.

"I do think that may be where it ends up, even though that's not where we want it to end up," said Ed Lazere, executive director of the D.C. Fiscal Policy Institute and a leader of a coalition called No D.C. Taxes for Baseball.

"It's an uphill battle," Lazere said of stopping the stadium. "Our chances, if we had a vote today, are pretty slim. I don't think we'd win."

With the mayor out of town until Sunday, aides have fanned out to sell the plan at community meetings across the city, including a push in Southwest Washington near the proposed location of the stadium.

At the same time, Williams's legislative staff has begun to seek ways to show how millions of dollars could be generated by the stadium and invested in other needs.

Shortly after Major League Baseball announced that the Montreal Expos would relocate to Washington next spring, city officials projected annual benefits of $12 million to the city from a new stadium. They said the money would come from taxes on spending by baseball fans at restaurants, hotels and stores near the ballpark and income taxes paid by players and other team employees living in the District, among other sources.

Several sports economists have said that such projections are typically overstated and that new stadiums do not bring significant additional revenue to a city.

The mayor has since floated the idea of finding an additional $20 million a year for schools and other pressing needs. And mayoral aides who will testify at the public hearing said this week that they hope to appease critics on the council by offering new details on how the stadium could generate money for such a fund.

"The criticism is that in the text of the [stadium] legislation, nothing seems to be concrete or hard" in terms of money for neighborhood investments, said a mayoral staff member who spoke on the condition he not be identified because plans have not been completed.

"The mayor said, 'Look at it and make sure it's concrete,' " the staff member said. "We're looking at opportunities to address that need. . . . What the mayor's hearing [from critics] is to not be vague, to show economic benefits and not just lip service."

A D.C. Council committee is scheduled to mark up the stadium legislation Nov. 3, and the full 13-member council is to take a first vote Nov. 9. Williams hopes to gain approval before the end of the year, when three new council members who oppose the plan probably will take office.

Both sides speculate that council members will offer numerous amendments to the legislation, including one from Adrian M. Fenty (D-Ward 4) to force the baseball team to remain at Robert F. Kennedy Memorial Stadium. But even Fenty acknowledges that stopping the new stadium is unlikely.

"At this point, I don't think that there's going to be enough to stop it," he said. "The mayor and some council members are so far out on a limb on this one, almost nothing could stop it."

Under the agreement negotiated by the city and Major League Baseball, the stadium would be financed through a gross-receipts tax on large D.C. businesses, rent payments by the team and taxes on tickets and merchandise sold at the ballpark.

Opposition to the plan is coming largely from two camps. One is a group of hard-liners in Lazere's coalition, including activists for schools, housing, health care, libraries, the environment and other causes. This group is fundamentally opposed to using public funds for a stadium.

The second group is made up of residents across the city who have told officials at community meetings that they will support the team and stadium as long as the mayor promises additional investment in neighborhoods.

Chris Weiss, a spokesman for Friends of the Earth, an environmental organization that is part of the hard-line coalition, acknowledged that the group's effectiveness has been limited. Several dozen coalition members demonstrated outside the Wilson Building two weeks ago. But a follow-up protest in Chinatown last week brought only 12 people, who distributed fliers to bemused passersby.

"This coalition is very broad," Weiss said. "We do advocate specific issues, but we don't have the organizing capacity."

The mayor's office seems to be listening more closely to residents who speak at community meetings.

Chris Bender, a spokesman for the city's Office of Planning and Economic Development, said city leaders decided not to stage large pro-baseball rallies to solicit support, but instead to attend regularly scheduled neighborhood meetings.

At the presentations, city officials have argued that the stadium will not replace any school or library projects but enhance them by increasing retail and other business investment, which will bring additional funds to the city.

"I know it's baseball, but we want to be presenting this in the same way as though a new department store and grocery store were coming to the neighborhood," Bender said.

The mayor attended one community meeting last week in Ward 7, where residents said they would support baseball if he also promised to champion such issues as schools and a new hospital east of the Anacostia River.

The day Williams departed for China, about 15 aides, including City Administrator Robert C. Bobb, huddled with a half-dozen neighborhood leaders in Southwest near the proposed stadium site. The residents questioned the officials about parking, public safety, displacement of businesses and retail development.

"So many people seem to focus on financing," said Andy Litsky, a Ward 6 activist who attended the meeting. "I'm not particularly in favor of the way it's structured, but we need to know: If this passes, how can we make it work?"

Mayor Anthony A. Williams directed staff members to show concrete benefits of a new stadium. Council member Adrian M. Fenty says the mayor and others have gone far out on a limb for the stadium.