Story highlights Sen. Al Franken is under investigation from the Senate Ethics Committee

Senate Minority Leader Chuck Schumer weighed in Tuesday afternoon

(CNN) Embattled Sen. Al Franken will make an announcement Thursday, his office told reporters, as calls for the Minnesota Democrat's resignation -- led by female senators and later including party leaders such as Senate Minority Leader Chuck Schumer -- rapidly gained momentum Wednesday.

Thirty-two Democratic senators -- 13 female and 19 male -- called on Franken to resign as allegations of sexual harassment against him continue to mount. Republican Sen. Susan Collins also called on Franken to quit.

In a statement on Facebook, New York Sen. Kirsten Gillibrand wrote: "While Senator Franken is entitled to have the Ethics Committee conclude its review, I believe it would be better for our country if he sent a clear message that any kind of mistreatment of women in our society isn't acceptable by stepping aside to let someone else serve."

Sens. Claire McCaskill of Missouri, Patty Murray of Washington, Maggie Hassan of New Hampshire, Kamala Harris of California, Tammy Baldwin of Wisconsin, Debbie Stabenow of Michigan, Sen. Heidi Heitkamp of North Dakota, Maria Cantwell of Washington, Dianne Feinstein of California, Tammy Duckworth of Illinois, Elizabeth Warren of Massachusetts and Mazie Hirono of Hawaii also joined in the call for Franken to resign.

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