The White House is doubling down on President Donald Trump’s unsubstantiated claim that then-President Barack Obama had him wiretapped during the campaign.

And on the Sunday shows, White House officials and allies presented zero new evidence to corroborate those eye-popping assertions. Instead, current and former administration officials struggled to make sense of the string of early-morning tweets the president fired off on Saturday, when Trump charged that Obama was a “[b]ad (or sick!) guy” engaging in “McCarthyist” tactics.

Sarah Huckabee Sanders took the first shot at it, appearing on ABC’s This Week to try to defend Trump’s allegation that then-President Barack Obama ordered the FBI to wiretap him and his team in Trump Tower (which Obama would not have been able to do—domestic wire-tappings for counterintelligence purposes have to be approved by the 11-member Foreign Intelligence Surveillance Court, and the White House isn’t part of the process).

Sanders didn’t clarify where the president was getting his information.

“Look, I think he is going off of information that he’s seen that has led him to believe that this is a very real potential,” Sanders said on ABC’s This Week. “And if it is, this is the greatest overreach and the greatest abuse of power that I think we’ve ever seen, and a huge attack on democracy itself. And the American people have a right to know if this took place.”

Sanders cited reports from The Guardian, the BBC and others, which purported to detail the FBI’s attempts to seek a Foreign Intelligence Surveillance (FISA) Court order to keep tabs on transactions between individuals close to the Trump campaign and Russian banks. None of those reports indicate Obama was involved in the process. That theory likely made its way to Trump via a Breitbart story summarizing conservative radio host Mark Levin’s speculation that Obama has launched a “silent coup” against Trump.

Even if all of the reporting on this is correct, the White House is misreading it, as Cato Institute senior fellow Julian Sanchez explained in a piece for Just Security.

Sanders’ defense of her boss followed a statement from White House Press Secretary Sean Spicer early Sunday morning doubling down on the unsubstantiated claim that Obama ordered wiretapping of Trump’s team. The White House did not provide evidence beyond the president’s initial tweets—instead asking Congress to investigate the possibility of wrongdoing by the Obama administration.

“Reports concerning potentially politically motivated investigations immediately ahead of the 2016 election are very troubling,” Spicer said. “President Donald J. Trump is requesting that as part of their investigation into Russian activity, the congressional intelligence committees exercise their oversight authority to determine whether executive branch investigative powers were abused in 2016.”

Spicer added that neither the White House nor Trump will comment further “until such oversight is conducted.” Obama denied through a spokesman that his White House ever “ordered surveillance on any U.S. citizen.”

Regardless, Sanders did her best to argue that the president’s allegations were grounded in fact.

“I think the bigger story isn’t who reported it, but is it true,” Sanders said. “And I think the American people have a right to know if this happened because if it did, again, this is the largest abuse of power that I think we’ve ever seen.”

On NBC’s Meet the Press, former Director of National Intelligence James Clapper flat-out denied that the FISA court authorized surveillance of Trump Tower, but didn’t clarify if the FBI and Justice Department sought such authority. Clapper, who once misled Congress about the National Security Agency’s surveillance capabilities before the revelations by Edward Snowden, said he would have been aware of a FISA court order of this magnitude.

“There was no such wiretap activity mounted against the president-elect at the time as a candidate or against his campaign,” Clapper added.

Former Attorney General Michael Mukasey, however, took the opposite stance, speculating that it was likely the FISA court that authorized surveillance of Trump associates, but noting he didn’t have direct knowledge either way.

The story is likely to dominate headlines for the next week—a narrative that could undermine the White House’s efforts to gin up support for a new version of the travel ban and for its Obamacare replacement plan. The administration is expected to release both of those this coming week. But the president’s charges that Obama conspired to monitor his campaign communications will undoubtedly consume the public’s focus.

And those charges are also confusing for his Republican allies on the Hill.

“It would probably be helpful if he gave more information,” Republican Sen. Susan Collins, a member of the powerful Senate Intelligence Committee, said on CBS’ Face the Nation. “But it also might be helpful if he just didn't comment further and allowed us to do our work.”

Florida Sen. Marco Rubio, also a member of the Senate Intelligence Committee, said on CNN’s State of the Union that he does not know what Trump is “talking about,” speculating whether “the president has information that is not yet available to us or to the public.”