US Senator Al Franken of Minnesota announced on Thursday that he will resign over allegations of sexual misconduct, the third US lawmaker to step aside over such allegations this week.

Later on Thursday, US Representative Trent Franks of Arizona said he would resign from Congress. Franks said he will step down Jan 31 amid a House Ethics Committee investigation of possible sexual harassment.

Punishment was swift for Franken since accusations began surfacing three weeks ago. The 66-year-old former comedian, who had been seen as a rising star in the Democratic Party, said on the Senate floor that he would be leaving in "coming weeks".

He denied wrongdoing, but said he believes he can no longer do his job effectively. Franken said that he ultimately would have been cleared.

"Some of the allegations against me are simply not true," he said. "Others I remember very differently."

Franks, a Republican, said in a statement that he never physically intimidated, coerced or attempted to have any sexual contact with any member of his congressional staff.

Instead, he said, the dispute resulted from a discussion of surrogacy. Franks and his wife have 3-year-old twins who were conceived through surrogacy.

Franks said he "became insensitive as to how the discussion of such an intensely personal topic might affect others". He said he regrets that his "discussion of this option and process in the workplace" with two female staffers made them feel uncomfortable.

Michigan Representative John Conyers, a Democrat and Congress' longest-serving member, resigned on Tuesday.

Following the downfall of the Hollywood movie mogul Harvey Weinstein, who was accused in October of rape and other acts of sexual misconduct by actresses and other women, there has been a rising flurry of sexual harassment and assault allegations against powerful figures in politics, media and entertainment in the US.

Time magazine on Wednesday named as its Person of the Year the "silence breakers", people who have come forward on sexual harassment to reveal a broader pattern of how they are often treated in the US workplace.

"Seventy percent of Americans say recent media stories about such abuse represent a broader pattern of how women are often treated, rather than being isolated incidents," said Robert P. Jones, the CEO of Public Religion Research Institute (PRRI). He made his comments in a presentation on Tuesday of the eighth annual American Values Survey at the Brookings Institution in Washington.

Partisan divisions are transcended in one area-by Americans' widespread belief that recent stories of sexual harassment and assault are part of a larger pattern, according to the survey.

There are modest but significant differences across lines of gender and party affiliation. Nearly eight in 10 women (78 percent) and more than six in 10 men (63 percent) see recent allegations of such behavior as part of a broader pattern of how women are treated, the PRRI said in a release.

More than seven in 10 Democrats, or 77 percent, and independents (73 percent) say that recent stories of women being sexually harassed and assaulted in the workplace are part of a broader pattern,and roughly six in 10 Republicans (59 percent) agree as well, it said.

The issue of sexual harassment, amplified by the#MeToo social media hash tag campaign in which women have recounted some of their own experiences, has rocked Washington, with at least four sitting members of Congress under ethics clouds, Agence France-Presse reported on Thursday, without giving names.

The recent sexual harassment cases in the US have been widely followed by social media in China. A topic with the hash tag of #HarveyWeinsteinsexualharassmentcase#, for example, generated 15,000 postings and 82.6 million views on Sina Weibo, a Twitter-like microblogging service, by Thursday.

Internet users also discussed other harassment reports, including those about US Transportation Secretary Elaine Chao, who said on Tuesday that she had suffered a "me too" moment of sexual harassment.

A Weibo subscriber known as "gushuichanchan" tweeted, "Surprisingly, there isn't yet an outburst of reports in the entertainment circle in China following such scandals in the US. I believe there would be no fewer such acts; silence breakers have yet to come forward. Hopefully, those mean beasts would get the warning message."

The Associated Press contributed to this story.

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