Walter S. Orlinsky, the ebullient president of Baltimore's City Council, pleaded guilty today to a U.S. extortion charge, but vowed on the courthouse steps minutes later to rebuild the "broken dreams" of his political career.

In a U.S. District Court room jammed with relatives, reporters and fellow council members, Orlinsky, 44, admitted accepting $2,532 in kickbacks in June 1981 to help a Philadelphia firm get a lucrative sludge-hauling contract with the city.

Scheduled to go on trial this week, Orlinsky made a last-minute switch and agreed with federal prosecutors to plead guilty to a single extortion count in the 12-count indictment that was brought against him last April. The indictment had charged him with accepting more than $10,000 in kickbacks.

His shoulders slightly stooped and his eyes brimming with tears, Orlinsky also told presiding Judge Norman P. Ramsey he had agreed to resign his City Council presidency, pay the city of Baltimore $10,032 in restitution and consent to disbarment from his law practice.

Prosecutors recommended that Orlinsky be sentenced to 15 months in prison and a $1,000 fine. Judge Ramsey set the sentencing date for Oct. 26.

With his wife Jo-ann and son Eric at his side, Orlinsky walked out to the front steps of the courthouse after the 45-minute plea hearing and told reporters: "My present is barren and full of remorse. [But] in my future, there will be new dreams." At another point he said, "there are new faces and issues about which the public will need to know and learn. Give them and the future its due." He declined to elaborate.

The FBI's Baltimore office has said Orlinsky's plea does not close the investigation of sludge-hauling contracts in the city.

Orlinsky's plea today came after an emotion-packed session of the City Council on Monday at which the customarily jovial council president announced his decision to plead guilty and resign from the presidency.

The announcement set off City Hall rumors about his possible successor, with council vice president Clarence H. (Du) Burns viewed as a front runner.

By pleading guilty, Orlinsky avoided what had promised to be a prolonged trial giving inside details of city contracting procedures and intimate glimpses of Orlinsky's private life.

In a 16-page "statement of facts" read in court today by Assistant U.S. attorney Richard Dunne III, Orlinsky was accused of accepting four cash payments totaling $10,032 from Edward J. Russell, a lobbyist for Modern-Earthline Companies, a Philadelphia-based sludge-hauling firm. According to the statement, Russell at one stage began cooperating with FBI investigators, concealing a tape recorder on his body to record conversations with Orlinsky.

Dunne said the kickbacks were devised by Modern-Earthline making phony "consulting" check payments to Russell, who cashed the checks and gave the money to Orlinsky.

One check for $2,985, Dunne said, contained a shorthand note on it indicating that the money was intended ultimately for Orlinsky, identified in the note by a "code name." Dunne did not say what the name was.

In exchange for the kickbacks, Dunne said, Orlinsky used his official influence to help Modern-Earthline get a two-phase contract in 1980 to haul city sludge to Garrett County in Western Maryland. The contract later was canceled when Garrett County officials objected.

One of the conversations with Orlinsky secretly recorded by Russell occurred at Orlinsky's home in January when the contract appeared in jeopardy. According to the government statement of facts, Orlinsky jokingly said of Modern-Earthline, "I wonder will they honor their commitment to me." Russell answered, "They'll have to," to which Orlinsky said, "What am I gonna do, sue 'em?"

Orlinsky also was originally charged with accepting another $1,000 from Russell on behalf of two other sludge-hauling firms. By this time, however, prosecutors said, Russell was cooperating with them, and the two firms were unaware of the alleged kickbacks.

In another secretly recorded conversation, according to the statement of facts, Russell told Orlinsky he was going to demand a $5,000 retainer from the two firms, to which Orlinsky replied, "With all the up-front expenses, just worry about me for a grand. Okay?"