House Intelligence Committee Chair Devin Nunes (R-Calif.) and Ranking Democrat Adam Schiff (Calif.) expressed doubt, March 15, about President Trump's claim of a 2016 wire tap at Trump Tower. (Reuters)

Here is a brief list of people who have said that President Trump's allegation that President Barack Obama ordered a wiretap of Trump Tower during the 2016 presidential campaign is simply not true:

1. Devin Nunes

The Republican chairman of the House Intelligence Committee, who has been one of the few defenders of Trump's claims, made clear Wednesday that there is zero evidence to suggest Trump Tower was wiretapped.

“I don't think there was an actual tap of Trump Tower,” said Nunes (Calif.). He added that if you are taking Trump's tweets literally — which he said you shouldn't do — then “clearly the president was wrong.”

2. James R. Clapper Jr.

The former director of national intelligence made clear in an interview with NBC's Chuck Todd that no wiretapping happened. “There was no such wiretap activity mounted against the president, the president-elect at the time, or as a candidate, or against his campaign,” Clapper said. He also offered a total and unequivocal denial that a Foreign Intelligence Surveillance Court warrant had been issued to create such a wiretap.

3. Former president Barack Obama

In a statement issued shortly after Trump tweeted the wiretapping allegations, a spokesman for Obama said: “A cardinal rule of the Obama administration was that no White House official ever interfered with any independent investigation led by the Department of Justice. As part of that practice, neither President Obama nor any White House official ever ordered surveillance on any US citizen. Any suggestion otherwise is simply false.”

4. James B. Comey

The FBI director, who is set to testify on Capitol Hill on the matter on March 20, was so outraged by Trump's allegation that he pushed, unsuccessfully, to have the Justice Department publicly refute it. The New York Times wrote:

Mr. Comey’s request is a remarkable rebuke of a sitting president, putting the nation’s top law enforcement official in the position of questioning Mr. Trump’s truthfulness. The confrontation between the two is the most serious consequence of Mr. Trump’s weekend Twitter outburst, and it underscores the dangers of what the president and his aides have unleashed by accusing the former president of a conspiracy to undermine Mr. Trump’s young administration.

Against such strong denials from people in a position to know, the White House has offered up, well, not much. Trump has largely gone silent since making the allegations 10-ish days ago. His White House senior aides have been backpedaling; the latest being White House press secretary Sean Spicer's decidedly odd argument that “wire tapping” and wiretapping are simply not the same thing. (Breaking news: They are!)

As I wrote at the time that Trump leveled these very serious allegations: The burden of proof was on him. To suggest that a former president orchestrated a listening program using the tools and resources of the federal government during a heated national campaign is a big charge. To do so without providing evidence — then or now — is eye-popping.

The repercussions of such charges should be serious. After all, this is conspiracy theorizing at the top levels of government. But they almost certainly won't be, as a Republican Congress is unlikely to scold a Republican president so new to the White House. And Trump, if past is prologue, will somehow declare victory and move on.

Top lawmakers on the House Intelligence Committee set a Monday deadline for President Trump's Justice Department to produce evidence to back up his claim that former president Barack Obama wire tapped him during the 2016 election. (Reuters)