President Donald Trump dismissed as “FAKE NEWS” any suggestion that he “colluded” with Russia, weighing in on an issue that has shadowed his young presidency hours before a House committee is to hold a hearing that will examine questions of Russian interference in the 2016 elections.

In a series of early morning tweets, Mr. Trump also returned to the election results and said that Democrats “made up and pushed the Russia story as an excuse for running a terrible campaign.”

Despite a favorable map that gave them a “big advantage” in the electoral college, Democrats still lost, Mr. Trump wrote.

The president was silent on another question that is expected to be taken up when Federal Bureau of Investigation Director James Comey appears before the House Intelligence Committee: whether former President Barack Obama wiretapped Trump Tower during the campaign.

Two weeks ago, Mr. Trump sent out a series of tweets alleging without evidence that Mr. Obama had tapped his phones at Trump Tower, his home and campaign headquarters in Manhattan. He called the former president a “bad (or sick) guy!”