There is overwhelming evidence the Obama administration wiretapped President Donald Trump before Trump was sworn in as president, and Democrats are trying to cover that up, conservative talk radio host Mark Levin said Sunday.

Trump claimed in a series of tweets Saturday, without offering any evidence, that former President Barack Obama ordered wiretaps at Trump Tower.

The allegations came as calls mounted for Attorney General Jeff Sessions to resign for not admitting during his confirmation hearing he had contacts with Russian Ambassador Sergey Kislyak during the campaign. Sessions announced last week he would recuse himself from any investigation into Trump campaign ties to Russia’s efforts to influence the 2016 presidential election.

Former National Director of Intelligence James Clapper and Sen. Mark Rubio, a member of the Senate Intelligence Committee, said on several Sunday morning talk shows they were unaware of any such surveillance.

But Levin told “Fox & Friends” said the question is not whether there was any surveillance but the extent of the surveillance.

“The FBI sought and was granted a Foreign Intelligence Surveillance Act court” order, Levin said, despite Clapper’s comments that no such order was issued for Trump Tower to any of the agencies under his jurisdiction.

Levin said the FBI, CIA, National Security Agency, the Justice Department and two other agencies began investigating Trump and his team in October as part of the investigation into Russia’s activities. He quoted a story in the Guardian as saying the FBI “applied for a warrant from the Foreign Intelligence Surveillance Court in order to monitor four members of the Trump team” during the election campaign.

He also accused Democrats of trying to cover up the surveillance.

Former White House press secretary Josh Earnest explained why the allegations are ludicrous on ABC’s “This Week.”

“This may come as a surprise to the current occupant of the Oval Office, but the president of the United States does not have the authority to unilaterally order the wiretapping of an American citizen,” Earnest said.

“If the FBI decided to use their wiretapping authority in the context of the counterintelligence or criminal investigation, it would require FBI investigators, officials at the Department of Justice going to a federal judge, and making a case, and demonstrating probable cause to use that authority to conduct the investigation. That is a fact.”

A spokesman for Obama dismissed Trump’s allegations Saturday, saying it didn’t happen.

“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 U.S. citizen. Any suggestion otherwise is simply false,” Obama spokesman Kevin Lewis said.