Ex-Senator Jeff Flake's advice to Republicans ahead of impeachment trial

As the impeachment trial of President Trump gets underway this week, Senate Minority Leader Chuck Schumer says he'll force votes to call four witnesses at the trial if Majority Leader Mitch McConnell doesn't do so. Democrats will need the votes of four Republicans. Republican Jeff Flake of Arizona, who served in the Senate from 2013 until last year, joins “CBS This Morning” with his advice for members of his party.