WASHINGTON — A new ad supporting Hillary Clinton uses the words of Republican leaders and appointees to make the case that Donald Trump is unfit to lead the United States. The spot is part of an effort by the Democratic nominee and her allies to frame stopping Trump — and backing her candidacy — as a national cause for Americans of all political persuasions. The 30-second spot shows clips of 2012 Republican nominee Mitt Romney, former Secretary of Defense Robert Gates, former CIA Director Michael Hayden and others questioning Trump’s temperament and foreign policy experience. Trump’s comments “create a clear and present danger,” says Hayden.