Max L. Friedersdorf, President Reagan's top liaison with Congress, resigned his post yesterday and sources say he will be replaced by one of his deputies, Kenneth M. Duberstein.

Friedersdorf, 52, will become U.S. consul general to Bermuda. His resignation is effective Jan. 2.

David Gergen, White House communications director, said Friedersdorf's decision was voluntary. Friedersdorf was hospitalized earlier this year with a serious asthma attack but Gergen quoted him as saying yesterday that his job change is not for health reasons.

In response to questions, Gergen said also that Friedersdorf is "absolutely not" being pushed out for reasons related to his performance but is held in "high regard."

"He has reached a point in his life when he would like to begin a second career," Gergen said, adding that Friedersdorf had made clear "early on" that he would not want to serve the full four-year term.

"He's just had a hard year," a White House official said.

One administration source said that Duberstein, Reagan's chief lobbyist in the House of Representatives, would be named today to succeed Friedersdorf.

A 37-year-old native of Brooklyn, N.Y., Duberstein served during the Ford administration as deputy undersecretary for legislative affairs, and had served before that as director of congressional and intergovernmental affairs for the General Services Administration.

During the Carter years, he was in the private sector, serving as vice president and director of business and government relations for the Committee for Economic Development, a nonprofit public policy organization of business executives and university presidents.

Reagan, in his letter accepting Friedersdorf's resignation, wrote: "We could not have done it without you."

Reagan praised his aide for playing a "key role" in winning passage of the administration's economic recovery program and added, "We have been through some historic times together."

Friedersdorf, in his letter of resignation, said his year with Reagan fell "during a session of Congress which I believe will rank historically as one of major and longlasting significance for our country." He gave no reason for his move.

In accepting the Bermuda post, Friedersdorf will take a pay cut from $60,662 to $50,112, a White House official said.

A cordial, white-haired Indiana native, Friedersdorf left a post as chairman of the Federal Election Commission to join the Reagan White House staff as assistant to the president for legislative affairs. He was a veteran White House lobbyist, having served from 1971 to 1977 in the congressional liaison office under Presidents Nixon and Ford.

During the 1960s, Friedersdorf was administrative assistant to former representative Richard L. Roudebush (R-Ind.). He later worked as staff director for the Senate Republican Policy Committee.

Before getting into politics, he was as a reporter for the Louisville Times, the Indianapolis News and the Chicago Daily News.

His departure would be the first by a senior Reagan White House staff member, not counting national security adviser Richard V. Allen, who is on administrative leave pending investigation of his conduct.

Staff writer Helen Dewar contributed to this article.