Rep. John Conyers Jr. (Mich.), the longest-serving member of Congress, stepped aside as the top Democrat on the House Judiciary Committee amid growing internal pressure as an ethics investigation of sexual harassment allegations against him begins.

Conyers, 88, said he would not resign from Congress and instead would fight the allegations in the hope of reclaiming his spot atop the committee, which oversees federal laws and other legal issues. “I very much look forward to vindicating myself and my family before the House Committee on Ethics,” he wrote Sunday in a letter to House Minority Leader Nancy Pelosi (D-Calif.).

Conyers settled a sexual harassment complaint brought by a former staffer in 2015, leaving her on the payroll as a temporary employee and paying out just under $30,000.

Pelosi issued a statement immediately after Conyers’s announcement: “I particularly take any accusation of sexual harassment very seriously. Any credible accusation must be reviewed by the Ethics Committee expeditiously. We are at a watershed moment on this issue.”

The announcement came after days of internal pressure on Conyers, particularly from Pelosi, to step aside from the leadership post, according to a senior Democratic aide familiar with the process.

It followed a Sunday morning dominated by the sprawling issue of sexual harassment and assault on the political news shows. Initially, on NBC’s “Meet the Press,” Pelosi declined to say whether Conyers would suffer any immediate penalty over the allegations.

“We are strengthened by due process. Just because someone is accused — and was it one accusation? Is it two? I think there has to be — John Conyers is an icon in our country,” Pelosi told NBC’s Chuck Todd, when asked whether Conyers should resign.

However, in a sign that she knew what was coming, Pelosi said she expected Conyers to do what’s necessary. “I believe he understands what is at stake here and he will do the right thing,” she said.

Members of Congress have said that the “due process” system is outdated and biased toward insulating the lawmaker from suffering penalties for misbehavior. “The whole system needs to have a comprehensive shift,” Rep. Jackie Speier (D-Calif.) said on ABC’s “This Week.”

Rep. Jackie Speier (D Calif.) says Congress must reform the way it deals with sexual harassment. (Clare Major)

Speier and Rep. Barbara Comstock (R-Va.) are the lead sponsors of legislation slated for a vote this week that would streamline the sexual harassment complaint process, amid growing accusations and revelations about members of Congress that are similar to those involving powerful men from Hollywood, the media and Silicon Valley.

The legislation also would require mandatory training on harassment and discrimination for all lawmakers, staff and interns who work in Congress. “There needs to be one standard for members,” Comstock said on “This Week,” noting that Conyers benefited from making a settlement payment that was never revealed until a BuzzFeed report last week. “No more secret payments.”

Conyers has denied any wrongdoing and said his payout was meant to resolve the issue and did not constitute an admission of culpability.

His payout came from the regular allowance for lawmakers for staff salaries and other administrative costs. As The Washington Post reported this month, a separate account overseen by the Office of Compliance has paid out more than $15 million in settlements of sexual harassment and other cases of discrimination.

Congress makes its own rules about the handling of sexual complaints against members and staff. Here's why it’s so hard to report sexual harassment in Congress. (Victoria Walker/The Washington Post)

One Democrat, Rep. Kathleen Rice (N.Y.), has suggested that Conyers should just resign from Congress altogether, something that Comstock voiced agreement for Sunday, citing how swiftly some high-profile media titans have fallen.

“We have to have the same kind of standards,” she said.

Speier, however, said the House Ethics Committee should add staff to handle the Conyers case “very swiftly” to determine the severity of the allegations. “If they’re accurate, I do believe that Congressman Conyers should step down” from Congress, she said.

Pelosi also suggested that Sen. Al Franken (D-Minn.), who is facing allegations of his own, was a different case partly because one of his alleged victims has publicly accepted his apology. Franken was recently accused of forcibly kissing an entertainer on a 2006 United Service Organizations tour before he joined the Senate, and several other women since then have suggested that Franken groped them while posing for pictures.

“I don’t think that you can equate Senator Franken with Roy Moore. It’s two different things,” the Democratic leader said, suggesting that the allegations against Franken are not nearly as severe as those against the Republican Senate candidate in Alabama.