Sen. Rand Paul has called for an investigation into former CIA Director John Brennan.

"BREAKING: A high-level source tells me it was Brennan who insisted that the unverified and fake Steele dossier be included in the Intelligence Report… Brennan should be asked to testify under oath in Congress ASAP," Paul tweeted Wednesday afternoon.

Former British intelligence officer Christopher Steele penned the dossier after he was hired by Fusion GPS, a research firm retained by Hillary Clinton's lawyers at Perkins Coie during the 2016 Presidential campaign.

It was the dossier that sparked the allegations against President Donald Trump that he colluded with Russia to win the election.

"I think we need to find the truth," Paul told Washington Secrets on Wednesday. He said that baseless investigations like the Trump-Russia probe should be prevented in future administrations, regardless of political affiliation.