We’ve seen this before in Ukraine: candidates up for election complaining that the vote is being rigged against them. Usually (because votes in Ukraine sometimes are, indeed, rigged), it’s a tactic to undermine the legitimacy of the vote and the person who wins. But it’s not something we would expect to see in the world’s signal democracy, the United States.

Without providing evidence to back up his claims, the Republican Party candidate for U.S. president, Donald J. Trump, has been claiming in late-night rants on Twitter that the election is being rigged against him.

He hasn’t provided any evidence because there is none. And the U.S. election system is so decentralized that it is extremely implausible that the vote could be fixed on a nationwide scale.

In recent weeks, Trump has consistently trailed his rival, the Democratic Party candidate Hillary Clinton, in nationwide polls. Since he tweeted on Oct. 11 that the “shackles have been taken off” him, and he could now “fight for America the way I want to,” he seems to have spent more time attacking senior Republicans than battling Clinton. If he loses the Nov. 8 election, it will not be because the vote was rigged, but because of his own failings, because voters judge him to be unfit for the presidency.

He has given voters plenty of evidence over this sordid campaign that this is indeed the case. The absurd claim that the vote is being rigged, and his refusal to say if he will accept the result of the presidential election, are just the latest pieces.

So Trump should take the advice U.S. President Barack Obama gave him on Oct. 18, and stop whining. Because with 17 days still to go to the election, he already sounds like a loser.