Top Democrat on the Senate Judiciary Committee Sen. Dianne Feinstein, D-Calif., sent a letter to Chairman Chuck Grassley on Thursday in which she called for more testimony from former FBI Director James Comey, Attorney General Jeff Sessions and other individuals as part of an ongoing probe into Russian interference in the 2016 election.

Feinstein wrote to Grassley, R-Iowa, telling him there is a unanimous belief that Comey should testify before the judiciary panel in order to address unanswered questions and that she is willing to subpoena him if he is unwilling.