Republican Mitch McConnell is threatening a 'scorched-earth Senate' if Democrats end the filibuster. They should do it, commentator Robert Robb says. #MitchMcConnell #Scorched #Filibuster For more Arizona news, sports and entertainment, follow azcentral on: Facebook - https://bit.ly/2N2Xqqc Twitter - https://bit.ly/2MsVLOM Instagram - https://bit.ly/2nPxgwm Online - https://www.azcentral.com