Anderson Cooper. Screenshot via CNN The unsubstantiated wiretapping allegations President Donald Trump lobbed at President Barack Obama nearly two weeks ago on Twitter have continued to haunt Trump.

Republicans and Democrats alike have denounced Trump's allegations. The president on Wednesday night essentially acknowledged that he had 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," Cooper said at the opening of his program. "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 pointed to a heated exchange that unfolded between the White House press secretary, Sean Spicer, and reporters on Thursday, in which Spicer attempted to defend Trump's unsubstantiated wiretapping claims. Cooper also referred to 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 backed up his assertions — as well as remarks a Fox News host made about investigations into potential ties between Trump associates and Russia.

Reps. Adam Schiff and Devin Nunes speaking with the media on Capitol Hill on Wednesday about the ongoing Russia investigation. REUTERS/Aaron P. Bernstein

Congressional inquiry turns up nothing

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

"Clearly, the president is wrong," Nunes said of his conclusion if Trump's tweets were to be taken "literally."

Senate Intelligence Committee leadership said in a joint statement on Wednesday that there was 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 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 were 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: