(Adds statement from Congressional Black Caucus chairman)

By Richard Cowan

WASHINGTON, Nov 28 (Reuters) - Some of Democratic U.S. Representative John Conyers' colleagues in the Congressional Black Caucus (CBC) are pressing the 88-year-old lawmaker to resign amid sexual harassment allegations against him, two senior House Democratic aides said on Tuesday.

The aides, who asked not to be identified, did not say how many lawmakers were involved in the effort but confirmed a report by CNN that it was under way.

One aide said Democratic Representative Cedric Richmond, the CBC chairman, was active in the move to get Conyers to step down and end a House of Representatives career that began with his first election in 1964.

Richmond issued a statement after meeting with Conyers on Tuesday that said: "Any decision to resign from office before the ethics investigation is complete is John's decision to make."

Richmond said he had a "very candid conversation" with Conyers "about the seriousness of the allegations against him, which he vehemently denies."

"The Congressional Black Caucus calls on Congress to treat all members who have been accused of sexual harassment, sexual assault, and other crimes with parity, and we call on Congress and the public to afford members with due process as these very serious allegations are investigated," Richmond said.

The Michigan congressman is the longest-serving House member and the dean of the CBC.

Aides to Conyers did not immediately respond to requests for comment.

On Sunday, Conyers said he was stepping down as the senior Democrat on the House Judiciary Committee pending a congressional ethics investigation.

He has denied allegations that he made unwanted sexual advances to some women who worked for him, but said his office had resolved a harassment case with a payment and no admission of guilt.

Conyers' troubles come as sexual harassment accusations in recent weeks have ensnared former Hollywood executive Harvey Weinstein and other politicians, including Republican Senate candidate Roy Moore of Alabama and Democratic Senator Al Franken of Minnesota.

The CBC was founded in 1971 and has 49 members in the House and Senate. It is an influential voice within the Democratic Party.

Following Conyers' announcement on Sunday that he was stepping down as the ranking House Judiciary Committee Democrat, House Democratic leader Nancy Pelosi called for "zero tolerance" on sexual harassment.

If Conyers were to resign, a special election would be held to fill his seat. (Reporting by Richard Cowan; Additional reporting by Eric Beech; Editing by Tom Brown and Peter Cooney)

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