Sen. Elizabeth Warren, D-Mass., accused President Trump of firing FBI Director James Comey to stop his probe of potential collusion between Trump's campaign and Russia.

"I think there's just no doubt given the timing that the reason Comey was fired is that Donald Trump wants to cut off any investigation into any connections that he has with his campaign and connections to the Russians," Warren told CNN Wednesday.

Warren is also calling for Deputy Attorney General Rod Rosenstein to testify under oath concerning whether Comey had requested additional funds for his probe into Russia's interference into the 2016 election.

"Well, if the justice department wants to deny that, then my view is that the judiciary committee should call him right now and have him testify under oath to exactly what Comey asked for," Warren said.

The Department of Justice knocked down reports Wednesday that Comey asked officials for more money for the FBI's investigation into Russia's meddling in the 2016 presidential election, just days before he was fired by Trump.

"Totally false," DOJ Spokesman Ian Prior told the Washington Examiner just minutes after the New York Times reported that Comey made that request.

Comey has been invited to testify before the Senate Judiciary Committee in a closed-door session Tuesday.