"I just can't leave now," said Trump, who has stepped up his campaigning for Republicans as Election Day approaches.
Secretary of State Mike Pompeo met with Kim earlier Sunday and had a conversation that Pompeo described as "good, productive" toward Pyongyang giving up its nuclear capabilities.
"As President Trump said, there are many steps along the way and we took one of them today," Pompeo said of the meeting. "It was another step forward."
After he left the meeting, Pompeo told South Korean President Moon Jae-in that Kim is ready to meet with Trump "as soon as possible," according to Moon's office.