John Bolton prepared to testify if subpoenaed by Senate

05:17

Former National Security Advisor John Bolton, who aides have told Congress was deeply disturbed by Trump's conduct towards Ukraine, is now willing to testify if he receives a subpoena from the GOP controlled Senate. Robert Costa joins Andrea Mitchell to discuss what kind of pressure this could put on Leader Mitch McConnell and moderate Republicans, as well as what Bolton's testimony could look like.