WASHINGTON — Sen. Al Franken, D-Minn., plans to resign Thursday, CNN and NBC News reported, after more than a half dozen women came forward over the past several weeks with allegations that he touched them improperly or made unwanted sexual advances.

Many of the allegations predate Franken’s Senate career, but the former comedian and Saturday Night Live cast member had already apologized and said he would “gladly cooperate” with a Senate Ethics Committee investigation of his behavior.

TV host Leeann Tweeden made the first allegations against Franken last month, and Franken’s Democratic colleagues appeared to accept his apology and endorsement of the ethics probe. But as additional allegations emerged, Franken’s support became tenuous, and on Wednesday dozens of Democratic senators — led by Democratic women — called for him to resign.

Franken will become the second member of Congress to announce his resignation this week due to sexual harassment allegations. Rep. John Conyers, D-Mich., first elected to the House in 1964, stepped down Tuesday after several women accused him of harassment. Conyers has denied any misbehavior and said he was being denied due process.

The latest report, which came from Politico, was based on an unidentified former congressional aide who said Franken tried to forcibly kiss her after her boss had left a broadcast studio. As she was collecting her belongings, the woman said she turned around to find Franken coming at her. As she ducked, she says he told her: “It’s my right as an entertainer.”

Franken, who was deferential to and apologized for his conduct to his first accuser, Tweeden, had a different response to the…