(CNN) President Donald Trump mocked Democrats Monday for their stony reactions during his State of the Union speech last week, saying that it was even "treasonous."

"They were like death and un-American. Un-American. Somebody said, 'Treasonous.' I mean, yeah, I guess, why not," he said to laughter.

"Can we call that treason? Why not," he added. He made the remarks during a speech at a manufacturing plant in Cincinnati, Ohio.

"I mean they certainly didn't seem to love our country that much," he said, adding it was "very, very sad."

Trump's comments came less than a week after he delivered his State of the Union address in which he preached the virtue of bipartisanship.

Read More