Donald Trump at a rally with supporters in Roanoke, Virginia, on Saturday. REUTERS/Jonathan Ernst In most elections since 1984, CNN has commissioned a poll with a debate-expectations question: Which candidate do you think will win the debates?

Campaigns seem to want low expectations entering debates: If voters expect a candidate to win, they worry that even a good performance will be scored as a "loss" because it fails to beat expectations.

Yet every time CNN asked about debate expectations, the candidate who "lost" the expectations game (that is, was expected by a plurality of voters to win the debate) went on to win the popular vote in the actual election.

You may recall Presidents Mitt Romney, John McCain, John Kerry, and Bob Dole from their "wins" in past expectations games.

This makes all the spin leading up to Monday night's debate look more than a little silly. Trump's campaign is being quite open about its candidate's light preparation, trying to foster the idea that he can win by not vomiting or using any racial slurs. Clinton's campaign is pushing back, humorlessly and exhaustingly as usual, with an insistence that Trump not be graded on a curve.

Clinton has indeed "lost" the expectations game, though not as badly as Barack Obama did four years ago: By a margin of 10 points, Gallup finds that likely voters expect her to win the debates. Back in 2012 and 2008, Obama's advantage was 25 points.

Obama did just fine despite losing the expectations game, just as Bill Clinton and Ronald Reagan did before him. This is probably because the only way to "win" the expectations game is to be the worse candidate.