In the 1860’s, when he didn’t like his showing in the Whig primaries, Lincoln quit and split the party, running as a third party candidate with fringe party with a dubious commitment to the constitution.
In 1873 the election was challenged and the justices of the supreme court sat on a special commission to decide the election. Issue? Voter Fraud. Some states sent competing and disputed “slates” of electoral college results. The issue of which were “official” had to be settled. Statute now makes this congresses’ responsibility.
In 2000 the vote was too close to blithely accept the estimated counts that were reported, and number of districts were using a faulty system for recording votes that was so egregious it allowed them to vote for multiple candidates without even intending to. It had to be handled by auto recounts and the automatic discard of faulty ballots lead to a real question as to who the people had actually elected vs who became the default winner after so many were denied the franchise.
Trump has refused to go on record, and thereby hamstring himself, as blithely accepting a closely contested race. His stated concerns have been that some districts my commit voter fraud and allow those adopting stolen identities (such as those voting on behalf of the deceased or illegal aliens posing as US citizens) to vote in a US election. Illegal aliens and the deceased, even if they are somehow managing to pay taxes are not entitled to vote in US elections. It is a crime. More importantly, it is not the will of the people.
Mr. Trump has any number of personality and character issues. Hillary has justifiably pointed them out, and he has fired back by pointing out that her character and personality are no better than his. This is the worst election cycle in the last 60 years. But the disingenuity of pretending not to understand the man’s unwillingness to commit ahead of time to the outcome in the event that there is demonstrably fraud is the cite Raymond Fiest’s favorite new word, the work of “idjits”.
Note: per Donna Pozdro Presidents and Presidential candidates who’ve said privately or publicly that election results were questionable or even worth challenging (legally or otherwise) include: Thomas Jefferson, Andrew Jackson, Samuel Tilden and Rutherford B. Hayes, Richard Nixon, Al Gore and George W. Bush, and John Kerry.