House and Senate leaders have denied it, a spokesman for the former president has denied it and on Monday the head of the FBI is expected to deny it - that Barack Obama had Donald Trump's offices in New York tapped before the November election.

Trump made the claim in a series of tweets and has continued to defend his  allegation as recently as Friday. But House and Senate leaders briefed by FBI director James Comey  have flatly denied such surveillance existed in bipartisan joint statements, leaving the White House virtually alone in asserting such claims.

Comey had privately encouraged Justice Department officials to refute Trump's claims soon after they appeared in a series of March 4 tweets. He is scheduled to testify before the House Intelligence Committee.

“I expect (Comey) will, and I hope we will put an end to this wild goose chase,'' California Rep. Adam Schiff, the House committee's ranking Democrat, told NBC's Meet The Press Sunday. "What the president said is patently false and the wrecking ball it created has now banged into the British allies and German allies and continuing to grow in terms of damage.''

Schiff referred to Trump's Friday remarks during a joint White House appearance with German Chancellor Angela Merkel, where the president once again defended his wiretap contention.