Special counsel Robert Mueller is set to appear on Capitol Hill on July 17.
According to CNN, his testimony will give Democrats their best chance to turn people against President Donald Trump.
Mueller’s appearance may also sway more Democrats toward the need to impeach Trump.
House Speaker Nancy Pelosi opposes impeachment and fears political backlash if they propose it.
House Judiciary Chairman Jerry Nadler said Attorney General Barr misrepresented the report, saying there was no collusion.