Key presidential advisers will ask President Reagan to nominate Thomas P. Puccio, the Brooklyn prosecutor who directed the Abscam political corruption cases and played a key role in the French Connection heroin prosecutions, to be U.S. attorney for the District of Columbia.

The decision to recommend Puccio, 36, was made yesterday by White House and Justice Department officials and made known to Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) and other party leaders, according to Republican sources.

Puccio is now the chief of the Justice Department's organized crime task force headquartered in Brooklyn. He declined to comment last night when asked about the possibility of his taking over the prestigious prosecutor's job here.

Charles F.C. Ruff, the current U.S. attorney here who was appointed by the Carter administration in 1979, had little comment on the reported nomination. "He's taking over the leadership of one of the finest prosecutor's offices in the country," Ruff said.

Although Ruff was appointed to a four-year term as U.S. attorney in Washington by the Carter administration, the federal prosecutor traditionally serves at the discretion of the president.

Sources said last night that Puccio was picked because of his strong reputation as a "heavy-hitter" who could take command of what the White House and the Justice Department have always believed is one of the most important federal prosecutor's offices in the country.

Yesterday's decision ended months of uncertainty over whom -- if anyone -- the Republicans would choose to succeed Ruff, whose term was to end in 1983.

Sources said Puccio became a candidate for the post only within the past several weeks, and reports of the decision surprised several assistant federal prosecutors who were unaware that Puccio was in the running.

The decision was reached during a late afternoon meeting of a working group of high ranking White House and Justice Department officials. No formal announcement of a nomination was planned until various formal background checks were completed, including FBI clearance. If nominated for the job, Puccio's appointment would be subject to confirmation by the Senate.

Sources indicated last night that the confirmation process could be unusually sensitive in this case because of Puccio's role in the Abscam investigations, two of which were prosecuted by the U.S. Attorney's office in Washington.

Speculation on a new prosecutor here had focused in the last five months on a handful of lawyers in the District who had expressed interest in the chief prosecutor's job. Several candidates have been moved through Justice Department and White House steps that comprise the nomination process, but none was chosen.

Among other candidates who had been actively supported for the post were Washington lawyer Paul Friedman, a partner in the local office of the Wall Street firm of White & Case; Joseph E. diGenova, chief legal counsel for the Senate Rules Committee; and Donald T. Bucklin, a partner in the Washington law firm of Wald, Harkrader and Ross.

Puccio has been a key investigator in several major narcotics and police corrpution cases in New York City, but his notoriety in law enforcement circles is linked to the Abscam bribery cases, in which FBI undercover agents, posing as Arab sheiks, offered money and gifts to members of Congress in exchange for political favors. The controversial cases ended with the convictions of six members of the House and one senator.

Unlike any other federal prosecutor's office in the country, the U.S. attorney's office here handles all local criminal cases, such as murder and robbery, as well as federal cases, such a major narcotics prosecutions. The federal prosecutor's office is split into two divisions for the U.S. District Court and the D.C. Superior Court, both supervised by the U.S. attorney and his deputies.

In the months before Ruff was nominated to the chief prosecutor's job in October 1979, local political leaders had lobbied extensively to get a black lawyer picked for the post. At the same time they pushed hard for support of a plan -- backed by the Carter administration -- to transfer control over local criminal cases from the federal to the local prosecutor's office. Ruff, who was acting deputy attorney general at the time of his appointment, had been the Justice Department's key contact in developing a plan for the District to take full control of the local criminal justice system.

Lobbying for a particular candidate by local political leaders was absent during this round of screening for the post. Meanwhile, the Reagan administration has made it clear that it does not support an effort to take authority to prosecute local criminal cases out of the hands of the U.S. Attorney's office.

Mayor Marion Barry, who had expressed disappointment when Ruff was selected over a local black lawyer supported by the mayor and other city political leaders, could not be reached for comment last night. Herbert Reid, legal counsel to the mayor, said that as far as he knew, Puccio's selection had been made without any "serious consideration by local members of the bar either black or white." Puccio, a registered independent, is not a member of the D.C. Bar.

Reid said, however, that he felt Puccio's experience as a narcotics prosecutor would be important to District law enforcement officials, who recently launched a major crackdown on drug dealers in Washington.

During his tenure with the Justice Department, Ruff served as the last of the Watergate special prosecutors and directed an investigation into former President Gerald R. Ford's campaign finances. The investigation cleared Ford.

The decision to recommend a new U.S. attorney here comes in the midst of the prosecution of John W. Hinckley Jr., who is accused of the attempted assassination of Reagan and the shooting of three others last March 30. Although Ruff has been supervising that case, it is expected his departure would have little effect on it because it has been handled on a day-to-day basis by veteran assistant U.S. Attorney Roger M. Adelman.

Puccio, a graduate of Fordham University law school, was with the U.S. attorney's office in New York's eastern district until December 1976, when he took over the organized crime task force.

As a federal prosecutor, he supervised a narcotics unit and prosecuted several police officers suspected of stealing heoin that had originated in the French Connection case.