Lincoln tried to wrestle down a clash of civilizations. Trump is ginning one up to get re-elected.

He doesn’t worry about inciting violence against those he slimes. When I asked him about that in 2016, he said that he thought the rabid mood and physical altercations at his rallies added an air of excitement, and that his political journey into the heart of darkness is what got him to No. 1, so why wouldn’t he continue on it?

The president who hates flies is like flypaper. No matter how you come at him, buzzing past his outrages and lies like the Republicans or landing hard on them like the Democrats, you get stuck.

Both parties end up caught and struggling in the sticky mess.

Nancy Pelosi was trying to keep the Democrats in the center-left lane, where their best chance of beating Trump lies. But with his vile “go back” rant against four American Democratic congresswomen, the president — at least for now — achieved his stated aim of “marrying” the speaker to the far-left squad.

Given some of the hyper-liberal ideas tossed out by the Democrats in the first round of debates, Pelosi will have to work harder than ever to keep her party’s image where it needs to be with the real base, as opposed to the Twitter base.

The Republicans typically prefer a more subtle racism to rev up the base. In the past, they have handed the racist ploys off to hidden allies, then denied knowledge of Willie Hortonesque efforts to rouse hate. It’s ugly and disorienting — even to many Republicans — to see the toads jumping directly from the mouth of a president.

But as the boorish Trump has told reporters, “I don’t really care about offending people.”

He doesn’t rely on division only for elections, like his predecessors; he uses it to govern. And while that is a tad embarrassing for Republicans, they know from half a century of experience that it works to stir up racial animus and label foes wild-eyed socialists and commies.