Rep. John Conyers on Tuesday announced his retirement from Congress while at a Michigan hospital, saying he is endorsing his son, John Conyers III, for the seat he has held for more than a half century amid growing sexual-misconduct allegations.

“I’m retiring today,” the 88-year-old Michigan Democrat said in a phone interview with a local radio station from a Detroit hospital, where he has been since last month after experiencing chest pains. “I want everyone to know how much I appreciate [their] support.”

Conyers, the longest-serving congressman, made the decision two weeks after sexual harassment allegations first surfaced and after returning last week to his Detroit-area district to discuss his political future with family and advisers.

The most recent accusations surfaced Monday and allege Conyers slid his hand up a woman’s skirt and rubbed her thighs while they sat next to each other in church during a service more than a decade ago.

The latest accusation comes amid mounting claims and after Conyers was hospitalized.

He made his announcement Tuesday on Praise 102.7’s “The Mildred Gaddis Show.”

Conyers’ endorsement of his son was unexpected, considering his great-nephew, Ian Conyers, a Michigan state senator, said earlier that Conyers would not seek re-election in 2018, instead of retiring, and that he would run for the open seat.

The Constitution does not allow for appointments to the House.

So while Conyers has endorsed his son for the seat, the process begins with the Michigan Democratic Party through its nomination process .Then voters decide in either a special election or the 2018 congressional elections.

The process begins with Conyers submitting a letter of resignation to Republican Gov. Rick Snyder, who under state law declares the seat vacant. Snyder also sets the dates for the special primary and general elections, almost certainly next year. The processes and procedures for the elections are then put in place by Michigan’s Secretary of State office.

The resignation announcement was also a surprise considering Conyers’ attorney, Arnold Reed, said last week that his client wouldn’t be forced from office.

"I am very proud that I am the dean of the Congress." — Retiring Michigan Democratic Rep. John Conyers

“The congressmen felt it was important to address the individuals who elected him … separate from those in Washington,” Reed said Tuesday, reportedly at Conyers’ side at an “undisclosed” hospital.

Conyers, the House's longest-serving member, has vehemently denied the allegations against him.

He declined to address questions Tuesday about his health and said the allegations -- which he said “goes with the game of politics” -- would not diminish his political legacy.

“Absolutely not,” Conyers said. “My legacy cannot be compromised or diminished in any way, but what we are going through now. This too, shall pass. … I am very proud that I am the dean of the Congress.”

The younger, Conyers, 27, would be a first-time political candidate. But has already been connected to an ethics issue, according to the Detroit Free Press. In 2010, the congressman had to reimburse the Treasury Department $5,682 for his son’s misuse of a taxpayer-funded Cadillac Escalade, the paper reports.

Conyers’s wife, Monica Conyers, was in 2010 sentenced to more than three years in prison for taking cash, as a Detroit council member, to support a Houston company’s sludge contract with the city.

The Constitution does not allow for appointments to the House.

So while Conyers has endorsed his son for the seat, the Michigan Democratic Party decides first through the nomination process, then voters decide in either a special election or the 2018 congressional elections.

The process begins with Conyers submitting a letter of resignation to Republican Gov. Rick Snyder, who under state law declares the seat vacant. The process special election is set by Michigan’s Secretary of State office.

Other possible Democrats candidates reportedly include Wayne County Sheriff Benny Napoleon, former state House Rep. Rashida Tlaib, and state Sens. David Knezek and Coleman Young, as well as Brenda Jones, a nonpartisan member of the Detroit City Council.

New York Rep. Jerrold Nadler, who took Conyers’ post as the ranking Democrat on the chamber’s Judiciary Committee, said after the announcement: “John has been a champion for justice his entire life, and there is no doubt that these allegations have taken a tremendous toll on him personally … .With that said, there can be no tolerance for behavior that subjects women to the kind of conduct that has been alleged.”

A few days after the first allegations surfaced on Nov. 20, Conyers stepped down as the top Democrat on the House Judiciary Committee. But fellow party members had increasingly called for him to step aside.

House Minority Leader Nancy Pelosi, D-Calif., said unequivocally last week that Conyers should resign, amid increasing accusations and backlash after she called him an “icon” on women’s issues and suggesting an ethics investigation must come before any decisions are made.

“Congressman Conyers should resign,” she said Thursday. “He has served our Congress and shaped consequential legislation [but] zero tolerance means consequences for everyone -- no matter the great legacy.”

Still, he had some Capitol Hill support, including from the Congressional Black Caucus, which Conyers helped found.

The group said last week that the accusations are serious, but did not call for his resignation.

The news website BuzzFeed on Nov. 20 reported the first allegation: Conyers' office paid a woman more than $27,000 under a confidentiality agreement to settle a complaint in 2015 that she was fired from his Washington staff because she rejected his sexual advances.

The House Ethics Committee announced the following day that it had begun an investigation into Conyers, after receiving allegations of sexual harassment and age discrimination involving staff members and about the congressman using "official resources for impermissible personal purposes."

The committee will reportedly continue with the investigation, despite Conyers’s resignation.

Later in the week, Melanie Sloan, a lawyer who worked with Conyers on the House Judiciary Committee, said she was called into the congressman's office to discuss an issue and found him “walking around in his underwear.”

Sloan worked on the committee in the 1990s, but it was not clear when the alleged incident occurred. She also claims Conyers often screamed at her, fired and re-hired her, criticized her for not wearing stockings and once even ordered her to baby-sit one of his children.

The allegation made public Monday was from Elise Grubbs, a cousin of another accuser, Marion Brown.

Brown reached a confidential settlement with Conyers over sexual harassment allegations, but broke the confidentiality agreement to speak publicly last week.

Grubbs says in an affidavit made public that she worked for Conyers in various roles from about 2001 to about 2013.

She also said that she saw Conyers touching and stroking the legs and buttocks of Brown and other female staffers on "multiple occasions."

Conyers is among several D.C. lawmakers -- including Minnesota Democratic Sen. Al Franken and Texas GOP Rep. Blake Farenthold -- facing problems amid the recent wave of sexual-misconduct allegations hitting Capitol Hill.

Fox News' Chad Pergram and The Associated Press contributed to this report.