(Reuters) - A bipartisan group of U.S. lawmakers has introduced a bill that would ban agreements to keep sexual harassment and discrimination claims out of court, amid a wave of sexual misconduct allegations against powerful men.  Members of the U.S. Senate and House of Representatives unveiled the bill on Wednesday, saying mandatory arbitration agreements had forced women to privately arbitrate misconduct claims, effectively silencing victims and enabling serial harassers.  An arbitration case is similar to a lawsuit, but the proceedings are typically confidential.  Dozens of prominent American men in politics, media and entertainment have been accused in recent months of sexual harassment and misconduct. In some of those cases, their accusers had been required to sign agreements with their employers to keep work-related legal claims in arbitration. The bill would make those agreements unenforceable in sexual harassment and discrimination cases brought under federal law.  Lawmakers said an estimated 60 million U.S. workers have mandatory arbitration agreements. The issue of sexual harassment was in focus in Washington on Thursday as Senator Al Franken, a Democrat from Minnesota, announced he would step down after several women accused him of unwanted touching. Franken has denied some of the claims and apologized to other accusers.  On Tuesday, Representative John Conyers, a Democrat from Michigan, resigned after allegations that he sexually harassed staffers. Conyers, who was the longest-serving member of Congress, has denied the claims. Business groups including the U.S. Chamber of Commerce and National Federation of Independent Business have said in the past that arbitration can benefit both employers and workers who want to keep their claims confidential.  The bill is sponsored in the Senate by Democrats Kirsten Gillibrand of New York and Kamala Harris of California, and Republicans Lindsey Graham of South Carolina and Lisa Murkowski of Alaska. It also has two sponsors from each party in the House.  The lawmakers were joined at a news conference in Washington by former Fox News anchor Gretchen Carlson, who sued former network chief Roger Ailes for harassment last year. The claims led to Ailes’ resignation and a $20 million settlement for Carlson. Ailes and Fox denied any wrongdoing.  Carlson said arbitration agreements like the one she signed with Fox allow harassers to stay in their jobs, even when victims are pushed out or fired. 