The number two Republican in the Senate charged Thursday that President Obama is "trying to influence the outcome" of the FBI investigation into Hillary Clinton's use of a private email server during her tenure at the State Department.

"Time and time again, the White House has projected its desired outcome of this investigation to the public, and worse, to those people conducting it," Texas Sen. John Cornyn said on the Senate floor Thursday afternoon.

The Senate majority whip has long called for a special counsel to take over the review of Clinton's email practices, but President Obama's latest defense of the Democratic presidential candidate sparked another warning that the Justice Department has a conflict-of-interest in the Clinton probe.

Obama praised Clinton last weekend during an interview with Fox News Sunday, and boosted her defense that some of the classified messages on her email account are categorized that way for bureaucratic reasons, and not because they raise real national security concerns.

"I also know, because I handle a lot of classified information, is that … there's classified and then there's classified," Obama said. "There's stuff that is really top secret, top secret and then there is stuff that is being presented to the president or the secretary of state that you may not want on the transom, or going out over the wire, but is basically stuff that you can get in open source."

Those comments were inappropriate, in Cornyn's estimation. "There is simply no way to read it that it doesn't run a serious risk of trying to influence the outcome the investigation," he said. "I hope that the attorney general, perhaps in light of the president's comments attempting to influence the investigation — I can think of no other reason why he would say what he did — I hope that the attorney general reconsiders her refusal to appoint the special counsel in this case."

Cornyn accused Obama of inventing a "meaningless distinction" within the category of classified information and further suggested that Obama was misrepresenting the facts of the case. "We know that some of Secretary Clinton's emails were classified even beyond confidential, to the secret and top-secret/special access program levels, some of the highest levels of classification," he said.

Obama denied trying to protect Clinton from the FBI. "I guarantee that there is no political influence in any investigation conducted by the Justice Department, or the FBI, not just in this case, but in any case," he said during the interview. "Nobody is above the law. How many times do I have to say it?"

Clinton maintains that no information on her private server was marked classified at the time it was sent or received, a distinction that might prevent prosecutors from establishing a case that she knowingly mishandled classified information. Some intelligence community experts believe that the significance of top-secret information would be clear to any national security official who saw it.