Contesting a state’s election

Contesting a state’s election is a much more difficult undertaking than merely seeking a recount. If the losing campaign believes that the vote in one or more states was inaccurately counted, or that voter fraud may have occurred, with ineligible votes being cast or eligible votes being rejected — and in large enough numbers to swing the outcome — then it could move for a special judicial proceeding under state law, known as an election contest.

But it would need to muster persuasive evidence to halt any vote-certification process, and quickly, according to Benjamin L. Ginsberg, an election lawyer who represented George W. Bush against Al Gore in their 2000 standoff.

And it would need to contest the results in as many states as are necessary to flip the result of the election — and possibly more, to cover its bets.

Persuading the electors

Election Day is Nov. 8, but the Electoral College does not meet until December. Theoretically, the loser of the national election could try to persuade electors to ignore the wishes of their states’s voters. But this would be exceptionally difficult.

Its members are chosen in each state: If Mr. Trump carries that state, the Republican slate is elected, and if Mrs. Clinton wins, the Democratic slate is elected (except in Maine and Nebraska, which have separate processes.) Individual electors are typically public officials and party leaders chosen with input from that party’s presidential campaign.

Mr. Trump’s best chance, were he to find himself in this spot, could be to try to convince Democratic electors that they should vote for a third candidate, like Senator Bernie Sanders, preventing Mrs. Clinton from getting to 270 electoral votes and throwing the election to the House of Representatives.

Alternatively, and just as theoretically, the defeated candidate could assert that the electors in a given state are unjust and ask that state’s legislature to appoint a new slate of electors, Mr. Hasen said.

Appealing to Congress

The Congress recognizes and counts the votes of the Electoral College. So Mr. Trump could plead with Congress not to recognize a state’s votes, or to challenge the way they were counted, Mr. Hasen said. But that would be uncharted territory for Congress.