Michael Pertschuk, chief counsel of the Senate Commerce Committee, has been chosen by President Carter to be chairman of the Federal Trade Commission, according to a White House source.

Carter offered the post to Pertschuk during a White House meeting last Friday, the source said.

Pertschuk could not be reached yesterday for comment. Deputy White House press secretary Walter Wurfel refused to confirm or deny the report.

Pertschuk, 44, has been with the Commerce Committee for 12 years, and its chief counsel since 1968.

Three others who were considered for the FTC chairmanship were Robert Pitofsky, Michael R. Lemov and Joan Z. Bernstein.

Lemov is chief counsel of the House Subcommittee on Oversight and Investigations. Pitofsky, a Georgetown Law School professor who is associated with the Washington law firm of Arnold & Porter, put together the transition book on the FTC for the Carter administration. Bernstein resigned in April as acting director of the FTC's Bureau of Consumer Protection to join the Washington office of a Cleveland law firm.

As head of the consumer-conscious staff assembled by Chairman Warren G. Magnuson (D-Wash.), Pertshuk has been credited as a leading force for product safety, no-fault auto insurance, auto safety and other measures.

He has come to be regarded as one of the most - if no the most - influential staff members on Capitol Hill. As such, he has been accused by critics of being the person who really runs the Commerce Committee, of being too ardent a consumer advocate, and of lobbying committee members on behalf of positions he favors.

His defenders cite his effectiveness, his ability to get what Magnuson wants done, and the high level of expertise among the staff he has assembled.

The FTC has regulatory authority over a broad range of business practices such as advertising, consumer protection and the economic concentration of industries.

Two recent congressional studies of regulatory agencies noted that the FTC's operations vastly improved since the late 1960s, when it was a dumping ground for political patronage appointments.

A Ralph Nader group published a stinging indictment of the agency in 1969, which was echoed in an American Bar Association study called for by President Nixon.

A massive reorganization of the agency was begun in 1969 by FTC Chairman Caspar Weinberger and continued under his successor, Miles W. Kirkpatrick.

Pertschuk, who graduated from Yale College in 1954 and Yale Law School in 1959, is an adjunct professor at Georgetown Law School.

He is a member of the American Civil Liberties Union and is on the board of trustees of the Consumers' Union. He is a member of the District of Columbia Bar Association.

The Pertschuk nomination must be voted on by the Senate. If confirmed, he would succeed Calvin J. Collier, who would remain a commissioner for the remainder of his term, which expires in 1982.

"I knew Mike had a meeting with the President, and I more or less expected that was the purpose of the meeting," Collier told a reporter last night.