The senators, including Sheldon Whitehouse and Chris Coons, said a letter they received from the FBI last month shows the agency gathered over 4,500 tips relating to Kavanaugh without any apparent further action by investigators.
According to that June 30 letter, written by FBI Assistant Director Jill Tyson, the most "relevant" of the 4,500 tips were referred to lawyers in President Donald Trump's White House whose handling of them remains unclear.
The agency was conducting a background check, not a criminal investigation, so "the authorities, policies, and procedures used to investigate criminal matters did not apply," Tyson's letter said.