PORTSMOUTH, N.H. — A beleaguered Donald Trump sought to undermine the legitimacy of the U.S. presidential election on Saturday, pressing unsubstantiated claims the contest is rigged against him, vowing anew to jail Hillary Clinton if he's elected and throwing in a baseless insinuation his rival was on drugs in the last debate.Not even the country's more than two centuries of peaceful transitions of political leadership were sacrosanct as Trump accused the media and the Clinton campaign of conspiring against him to undermine a free and fair election."The election is being rigged by corrupt media pushing completely false allegations and outright lies in an effort to elect her president," he said, referring to the several women who have come forward in recent days to say that Trump had groped or sexually assaulted them. He has denied the claims, calling the women liars.Earlier Saturday, Trump took to Twitter to warn that "100% fabricated and made-up charges, pushed strongly by the media and the Clinton Campaign, may poison the minds of the American Voter. FIX!""Hillary Clinton should have been prosecuted and should be in jail," he added.