Charles Krauthammer said that Donald Trump's hoped-for "pivot" toward being presidential and uniting the Republican Party may never come.

"I'm not sure that you can call these mistakes," Krauthammer said. "At some point you have to ask yourself, is he capable of conducting himself any other way?"

He said that the basic structure of Trump's campaign should be simple: talk about the failed record of the Obama Administration that is championed by Hillary Clinton.

"With any other candidate on the Republican side, this thing would be over," he said.

Krauthammer said that the only way Democrats can win is to argue for Trump's "unfitness" for office.

"Because if he crosses the threshold of fitness he wins, and that's what the election is all about."

Watch more of the discussion below.