"This is one of the highest-quality people that I have ever met. And everybody that knows him says the same thing. And these are all false, to me. These are false accusations in certain cases, and in certain cases even the media agrees with that," Trump said at one point.
"If we brought George Washington here," the president continued, "and we said, 'We have George Washington,' the Democrats would vote against him, just so you understand. He may have had a bad past. Who knows? He may have had some I think accusations made."
Kimmel said the president appeared unhinged and compared the conference to "the craziest voicemail from your mom ever."
"They could easily have sold this thing to Netflix as a comedy special," Kimmel added. "It went on and on and all over the place."
"They say Rod Rosenstein wanted to tape him to show everyone he's nuts? Not necessary, he did it himself," the comedian added, referring to the embattled deputy attorney general.
Kimmel also mocked the president over his claims of having a "very, very large brain" and his attempts to make light of the moment when the audience at United Nations General Assembly laughed "with" him this week.
"They were laughing at you. They were definitely laughing at you," Kimmel said. "This press conference was successful only in that he did not physically melt or explode during it.
"The craziest part is, I bet he thinks he nailed it."