Senior federal prosecutors are looking into whether there is any merit to allegations made against Hillary Clinton and the FBI's investigation into her during the election, a Justice Department lawyer told lawmakers in a letter on Monday.

Congressional Republicans have requested the appointment of a second special counsel to look into allegations relating to Clinton and the Clinton Foundation — including those relating to the Uranium One sale — and the investigation into Clinton's email server.

On Monday, the head of the Justice Department's legislative affairs office responded to those requests by confirming that "senior federal prosecutors" were "evaluat[ing] certain issues raised in your letters."

The letter to House Judiciary Committee Chair Bob Goodlatte — a response to two earlier letters from July and September — noted that the prosecutors will "report directly to the Attorney General and the Deputy Attorney General, as appropriate" with recommendations as to whether investigations "should be opened," "require further resources," or "merit the appointment of a Special Counsel."

Attorney General Jeff Sessions is due to testify before the House Judiciary Committee on Tuesday.

The letter from Assistant Attorney General Stephen Boyd did not confirm the existence of any investigation, and did not guarantee that the prosecutors' evaluation would lead to any investigations.

Boyd's letter specifically noted that "all allegations will be reviewed in light of the Principles of Federal Prosecution" and that "the Department will never evaluate any matter except for on the facts and the law. Professionalism, integrity, and public confidence in the Department's work is critical for us, and no priority is higher."

The letter comes in the wake of tweets and critical comments from President Trump about what he called the "lack of investigation" into "the Uranium to Russia deal, the 33,000 plus deleted Emails, the Comey fix and so much more."

Later, he raised the issue again: