District officials said yesterday they are soliciting bids for the estimated $13 million renovation to get Robert F. Kennedy Memorial Stadium baseball-ready, with construction to begin in December.

Major League Baseball plans to sell the Montreal Expos and move the team to Washington pending the D.C. Council's approval of a proposed new baseball stadium on the Anacostia waterfront near South Capitol Street. Beginning in April, the team would play at RFK until a new stadium is completed.

With a temporary home plate lying in the western corner of RFK's soccer field, officials from the city's planning office and sports commission guided reporters on a tour of the stadium yesterday. They said the field, locker rooms, dugouts and stands would be ready for play April 15, when the new Washington team would open its home season against the Arizona Diamondbacks.

The key elements include replacing seating for soccer that is in left field with retractable seats that would be removed for baseball; installing foul poles and backstops; cutting a baseball diamond into the grass; painting and carpeting the locker rooms; installing cables, phone lines and electrical wiring for the media; and fixing minor cracks in some parts of the concrete stands.

"The clock is ticking," said Mark Tuohey, chairman of the D.C. Sports and Entertainment Commission, which operates RFK. "But we are confident we can get the stadium ready in time."

Even as city officials were moving forward with plans to bring baseball to the District, protesters gathered on the steps of the Wilson Building to continue their opposition.

The group, a coalition of the D.C. Fiscal Policy Institute, Friends of the Earth and the National Taxpayers Union, is against the proposed use of public funds to renovate RFK and build a $400 million stadium in Southeast Washington by 2008. They released a letter to Mayor Anthony A. Williams (D), signed by 90 economists, which states that stadiums do not bring cities increased revenue and significant economic development.

"Because sports stadiums are not used most of the year, they do not stimulate much development outside the stadium," the letter stated. "Most modern stadiums include restaurants and other entertainment offerings, limiting the money that goes to neighboring businesses. . . . In short, it is dubious to justify the use of public funds to subsidize construction of a DC baseball stadium on economic development grounds."

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.

The plan is contingent on approval by the D.C. Council, which has scheduled a public hearing on the matter for Thursday. A council committee will mark up the stadium financing bill Nov. 3, and the 13-member council is scheduled to take a first vote Nov. 9. The final vote could come as early as Dec. 7.

"The District made a bad deal," said Henry J. Aaron, an economist with the Brookings Institution who signed the letter to Williams.

Scott Walsten, a fellow at the American Enterprise Institute, said studies have shown that new stadiums do little to revitalize neighborhoods. "There are only 81 games a year," he said. "People can only spend so much money on entertainment. You don't get any new spending, and whatever spending there is stays inside the stadium."

While city officials expressed confidence that RFK will be ready by April, they used the tour to make a case that the stadium cannot serve as a suitable, modern site for baseball for an extended period. Critics, including some council members and activists, have said the city should have the team remain at RFK rather than use public money to build a new stadium.

Over the past four years, the Sports and Entertainment Commission has sunk roughly $5.1 million into maintenance and upgrades on RFK, money that came from the commission's budget and not city coffers. The work included $1.8 million on a new scoreboard, $800,000 on five new hospitality suites, $444,000 on repairs to a lower roof that was leaking and $226,000 on a new sound system.

But officials said RFK has narrow concourses that create bottlenecks, fewer restrooms and concession areas than new stadiums and outdated press boxes from which it is difficult to see high fly balls.

Stephen M. Green, a top adviser to the mayor on economic and baseball issues, described the 42-year-old RFK as "an aging facility."

"The question is how sustainable it is and that it will not offer the revenue-generating opportunity that is a reality for pro sports these days," he said.

The view from the press box at Robert F. Kennedy Memorial Stadium is of a baseball diamond on a soccer pitch, with seats where the middle of left field should be.