Maryland House Speaker Benjamin L. Cardin ended months of speculation about his political future tonight by announcing that he will abandon his race for governor to run for Congress.

Cardin, 42, told an enthusiastic crowd of more than 100 supporters gathered at a hotel here that he decided to leave the governor's race because the leading contenders were from Baltimore and that could fracture his base of support.

Maryland Attorney General Stephen H. Sachs and Baltimore Mayor William Donald Schaefer have expressed interest in the governor's race, and Schaefer had taken a commanding lead in the three-way race, according to early polls.

"Therefore my sense of responsibility to both the Democratic Party and the Baltimore metropolitan area tells me to accept a new challenge and to put my talents and experience to work in a new direction," said Cardin.

Cardin was joined at his announcement by Rep. Barbara Mikulski (D-Md.), who is running for the U.S. Senate and will vacate the 3rd District seat that Cardin is now seeking. The district encompasses much of northern Baltimore and southern Baltimore County as well as a part of Howard County that includes Columbia.

"I want to be just like Mikulski when I grow up," Cardin joked.

Cardin is in his fifth term as a delegate in Annapolis and his second term as speaker of the House, positions that gained him praise for his expertise as a negotiator in the legislative process.

He said his decision, which he reached 10 days ago, was prompted in part by the turnover that is about to occur because of departures within Maryland's congressional delegation. Reps. Parren Mitchell and Marjorie Holt are retiring, and Mikulski is running against Rep. Michael Barnes for the Senate.

"A considerable leadership vacuum will be created -- a vacuum that must be filled by experienced and knowledgeable individuals," Cardin said, taking note of his years of legislative experience.

Reps. Steny Hoyer (D-Md.) and Tony Coelho (D-Calif.), who is chairman of the Democratic Congressional Campaign Committee, were also present last night.

Coelho, one of several Hill Democrats whom Cardin said he consulted before making his decision, said that his staff's research indicates Cardin is the best chance the Democrats have of retaining the House seat.

"We feel he will be an absolute winner" Coelho said. "He will win the seat and represent the people, but he will also be a factor in the House quickly."

Most of the Baltimore-area Democrats who had expressed interest in Mikulski's seat dropped out in recent weeks as they learned that Cardin was reevaluating his political ambitions. Only Baltimore City Councilman Timothy Murphy said last week that he is still interested in challenging Cardin for the nomination.

Cardin said that he will endorse neither Sachs nor Schaefer for the Democratic gubernatorial nomination. But Del. Paul Weisengoff (D-Baltimore), one of Cardin's chief backers, said yesterday that he expects most of the people who have supported the Cardin candidacy to switch now to Schaefer.

Weisengoff said he advised Cardin to try for the congressional seat. "I thought it was in Ben's best interest to run for Congress where . . . . "

"He wins," interrupted House Speaker pro tem Thomas Kernan (D-Baltimore County).

Cardin had faced an uphill battle in his gubernatorial bid, a struggle complicated by the fact that a relative, Jerome Cardin, has been implicated in Maryland's savings and loan crisis for his role as a minority stockholder in the troubled Baltimore thrift, Old Court Savings and Loan.

Cardin said today that his decision to seek office from a more geographically compact area had nothing to do with possible negative backlash from the state's thrift problems.

"The polling that I've done shows absolutely no fallout" from the savings and loan crisis, he said