The unsubstantiated wiretapping allegations President Donald Trump lobbed at former President Barack Obama have continued to haunt Trump ever since he tweeted the claims less than two weeks ago. 

Since then, Republicans and Democrats have denounced Trump’s allegations. The president on Wednesday night effectively acknowledged that he has no evidence to back up his original assertions. The bipartisan leaders of the Senate Intelligence Committee echoed that there were no indications to believe any wiretapping had taken place.

CNN’s Anderson Cooper on Thursday night took it a step further.

“Tonight, we know the president of the United States has no facts. No facts to back up his startling allegation that the former president of the United States, President Obama, wiretapped him in Trump Tower during the campaign,” Cooper said at the opening of his program.

Cooper pointed to a heated exchange that unfolded between White House press secretary Sean Spicer and reporters on Thursday, in which Spicer attempted to defend Trump’s unsubstantiated wiretapping claims. He also referenced comments Trump made during a Fox News interview Wednesday night.

“I’ve been reading things,” Trump said, pointing to a New York Times article that he indicated backs up his assertions — as well as remarks a Fox News host made about investigations into potential ties between Trump associates and Russia.

Congressional inquiry turns up nothing

Trump said he wanted a congressional investigation over the unsubstantiated wiretapping claims. House Intelligence Committee chair Devin Nunes said on Wednesday that the committee found no such evidence of an Obama-ordered spying operation against Trump.

“Clearly, the president is wrong,” said Nunes, a Republican, if Trump’s tweets are taken “literally.”

Senate Intelligence Committee leadership said in a joint statement on Thursday there is no indication that Trump Tower was targeted for surveillance during the 2016 election.

Despite the rebukes, the president and the White House have persisted.

Spicer indicated earlier this week that he was “extremely confident” the Department of Justice would find evidence to back up Trump’s claim. Trump intimated similar assertions on Wednesday night, saying, “I think you’re going to find some very interesting items coming to the forefront over the next two weeks.”

Former Republican presidential candidate Rick Santorum said in a CNN interview on Thursday night that Trump’s relentless wiretapping assertions are starting to hurt him.

“We’re not in an election anymore, and it’s not his opponent he’s throwing off,” Santorum said. “I think it’s him that he’s throwing off.”

Watch Cooper’s monologue below:

 

Without evidence, White House stands by Pres. Trump’s wiretap claim @andersoncooper is #KeepingThemHonesthttps://t.co/9yjYHBgHhC
— Anderson Cooper 360° (@AC360) March 17, 2017

Follow Business Insider Australia on Facebook, Twitter, LinkedIn, and Instagram.