Deficit hawk and Tea Party supporter Rep. Mick Mulvaney (R-SC), President Trump's choice to lead the powerful White House Office of Management and Budget, is slated to testify on Capitol Hill Tuesday and one of the lawmakers scheduled to question him is Sen. John McCain (R-AZ), who recently authored a plan for a massive defense spending increase that some supporters fear could be derailed by a new fiscal agenda. Mulvaney is scheduled to testify at hearings of the Senate Budget...