WASHINGTON — President Donald Trump's defense failed him at the opening of his Senate impeachment trial on Tuesday. Senate Majority Leader Mitch McConnell, R-Ky., had one job. He just had to collect 51 votes for the trial rules he had written, in close consultation with White House officials, to deliver Trump an acquittal quickly, quietly and with as few surprises as possible. He couldn't do it. Fellow Republicans balked at his plan so late in the game — moments before the start of the trial — that he had to order up handwritten changes sought by Democrats just to secure...