WASHINGTON — President Trump said on Monday that he had no intention of watching Robert S. Mueller III, the special counsel in the Russian meddling case, testify on Wednesday before Congress, denouncing Democrats for “wasting their time.”

Then he added, “Maybe I’ll see a little bit of it.”

Mr. Trump’s history of remaining glued to television news — especially when the coverage is about him — suggests that he is certain to be tuned in as Democrats on Capitol Hill use Mr. Mueller’s appearance to amplify the damning report about the president and the people in his orbit.

But ahead of the congressional hearings, Mr. Trump and his aides sought to dismiss them as nothing more than a desperate attempt to elicit from Mr. Mueller something that could justify impeachment proceedings.

“We had a total ‘no collusion’ finding. The Democrats were devastated by it. They went crazy. They have gone off the deep end,” Mr. Trump said during a lengthy question-and-answer session with reporters in the Oval Office, adding, “All they care about is a phony investigation.”