History and political scientists tell us that 20 days before election day is usually too late to turn things around in a presidential contest. But this isn't a usual election. And Wednesday night's third and final debate between Donald Trump and Hillary Clinton might provide Trump with a legitimate chance to get a winning message across to the public even at this late stage in the game. Luckily for Trump, he's starting to do that even as the pundits and news media don't seem to quite see it yet.

A look at the polls tells us Trump really needs to change the momentum in this election and thus, this debate is more crucial for him. Trump blew through the primaries and looked like he had a great chance to win the White House with his simple "Make America Great Again" message. It was a tailor-made slogan that effectively meant different good things to a lot of different people. But it hasn't been enough to get him over the finish line, especially in light of the "Access Hollywood" tape leak and the sexual assault allegations against him.

At this point, Trump is unlikely to come up with another rallying cry as good as "Make America Great Again," but he's coming close with a phrase that's starting to appear on his Twitter feed: "Drain the Swamp."

That's a pithy way to incorporate all the outrage over the Clinton Wikileaks revelations, the progressive movement's anger over what they see as a corrupt economy and government, and all the usual anti-Washington sentiment in America. It's what they used to call a "reform movement" campaign that can only plausibly be led by an outsider.

Just Tuesday, he gave new definition to that reform movement by promising to propose a Constitutional amendment for Congressional term limits if he's elected. That's a winning message for him that he should repeat at the debate again and again, because Congressional term limits have always been popular in the polls and term limits fits so perfectly into a "drain the swamp" message.

And yes, this call for reform includes the controversial "election is rigged" message that the intelligentsia from President Obama to even some Republican strategists are disparaging. They're half right, because Trump's best message on the campaign trail and in the debate will be to focus on an overall system he thinks is rigged against most Americans, not just election-rigging.