(CNN) President Donald Trump and former Vice President Joe Biden are engaging in a war of words about beating each other up.

On Wednesday, Biden said that if he and Trump were in high school, he would "take him behind the gym and beat the hell out of him."

Trump responded on Thursday, tweeting, "Crazy Joe Biden is trying to act like a tough guy. Actually, he is weak, both mentally and physically, and yet he threatens me, for the second time, with physical assault. He doesn't know me, but he would go down fast and hard, crying all the way. Don't threaten people Joe!"

This all feels like a preview of a Biden and Trump face-off come 2020. And, in fact, Biden versus Trump is probably the highest probability matchup compared to all the others at this moment in time, though it's still a relative long-shot.

Now, a word of caution: Early polls are early polls and who knows who might enter the presidential race. It's hard enough for polls to forecast a winner within a week of an election. It's entirely unreasonable to believe they can forecast a winner at this point.

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