WASHINGTON — Minnesota Sen. Al Franken announced Thursday he will resign from Congress in the coming weeks following a wave of sexual misconduct allegations and the collapse of support from his Democratic colleagues, a swift political fall for a once-rising Democratic star. “I may be resigning my seat, but I am not giving up my voice,” Franken said in the otherwise-hushed Senate chamber. Franken quit just a day after new allegations brought the number of women alleging misconduct by him to at least eight.