While in Vietnam, the president said he walked away from the summit with Kim because of a disagreement about economic sanctions on North Korea. But he gave another explanation for the failure of the talks on Twitter on Sunday evening.

“For the Democrats to interview in open hearings a convicted liar & fraudster, at the same time as the very important Nuclear Summit with North Korea, is perhaps a new low in American politics and may have contributed to the ‘walk,’ ” he tweeted. “Never done when a president is overseas. Shame!”

Lanny Davis, Cohen’s attorney, declined to comment on Trump’s tweet Sunday night.