WASHINGTON — Rep. John Conyers of Michigan, the longest-serving member of the House of Representatives, resigned Tuesday after his support among fellow Democrats collapsed amid accusations of sexual harassment by several female employees.

Conyers endorsed his son, John Conyers III, in a rambling radio interview with Detroit host Mildred Gaddis.

“I am retiring today, and I want everyone to know how much I appreciate the support, incredible undiminished support I’ve received,” Conyers said.

Conyers’ use of the word “retiring” rather than “resigning” left some uncertainty over when he was vacating the congressional seat he has held since 1965. Later in the day, however, he sent a letter to congressional leaders saying he was stepping down “effective today.”

Conyers’ replacement will be chosen in a special election.

The Detroit-area district is heavily Democratic, so Conyers’ departure should not affect the balance of power in the House. But it does set up a potential family fight: A great-nephew, state Sen. Ian Conyers, has publicly said he also intended to seek the seat.

The announcement by John Conyers came after House Minority Leader Nancy Pelosi, D-Calif., Congressional Black Caucus leader Rep. James Clyburn, D-S.C., and an increasing number of House members urged him to quit as former aides offered detailed accounts of inappropriate sexual advances he had made over decades.

A longtime civil rights activist, Conyers is the highest-profile political figure to be forced from office in the midst of a national debate over sexual harassment that began weeks ago with accusations against movie producer Harvey Weinstein.

Conyers has continued to deny any wrongdoing, although on Nov. 26, he agreed to step down as the top Democrat on the House Judiciary Committee.

The accusations against Conyers, 88, had preoccupied members of the Democratic leadership, who were reluctant to be seen pushing out a leading African-American member of Congress who was widely respected for his advocacy.

At the same time, Democratic activists have been pushing for the party to take the lead in cracking down on sexual misconduct. Democrats have been trying to argue that voters in Alabama should turn aside the Republican candidate for Senate, Roy Moore, because of accusations by several women that he had made advances on them when they were teenagers and he was in his 30s. One of the women has accused Moore of sexual assault.

The disclosure of accusations against Conyers began Nov. 20 when BuzzFeed reported that in 2015, he had used $27,000 in taxpayer money to settle a wrongful dismissal complaint made by a female aide, Marion Brown, who said she was fired for not giving in to his sexual advances.

Several other former aides, including his former deputy chief of staff, Deanna Maher, subsequently came forward, saying that Conyers had demanded sexual favors or touched them inappropriately.

Adding to the accusations, Washington ethics lawyer Melanie Sloan said that when she worked for Conyers two decades ago, he had discriminated against her because of her gender, publicly berating her and at one point ordering her to babysit his child. Conyers also called her to a meeting at which he showed up dressed in a shirt and underwear, she said.

Pelosi was blistered by other party members after she initially appeared to minimize the complaints against Conyers in a Nov. 26 appearance on NBC’s “Meet the Press.”

In that interview, Pelosi cast Conyers as “an icon in our country” who had worked to secure rights for women and was confronting a host of unverified accusations.

Sloan, the ethics lawyer who had accused Conyers, said that Pelosi later called her to apologize. Pelosi then issued a statement insisting that harassment victims should be able to talk openly about their experiences. Four days after her initial defense of the congressman, Pelosi called for his resignation.

Conyers, on Tuesday’s radio show, was emphatic that his legacy would not be diminished. “I want you to know that my legacy will continue through my children,” he said.

He also called for a public airing of settlements paid by other members of Congress as a result of sexual harassment allegations.

cathleen.decker@latimes.com