President Donald Trump on Sunday blasted the Senate’s "blue slip" tradition, calling it an unconstitutional affront to his appointment power and alleging that his rights have "been completely taken away from me in States that have just one Democrat United States Senator."The president is referring to his ability to nominate judges and U.S. Attorneys, accusing the custom of essentially giving Democrats veto power over his nominees.U.S. Sen. Chuck Grassley is defending the century-old process, saying he views it as a norm worth preserving for balance and state input.GRASSLEY REBUKES TRUMP'S PRESSURE TO 'HAVE THE COURAGE' TO SPEED UP NOMINATIONSBlue slips