White House officials are unable to point to any internal assessment to justify their contention that President Donald Trump has the legal authority to fire special counsel Robert S. Mueller III.

Many Republican and Democratic lawmakers are urging Trump to let the former FBI director complete his investigation of Russian election meddling and possible misconduct by the president and his campaign associates. Those pleas intensified last week when the president and his top spokeswoman signaled the White House has concluded he has the authority to do so.

The legal community is split on whether a sitting U.S. president has the legal authority to remove a special counsel.

Some experts say Justice Department rules that govern the appointment, supervision, conduct and termination of special counsels vest firing authorities in the attorney general. Others contend there is nothing in those rules to preclude a president from giving the termination order.

Watch: White House’s Sanders and Trump Imply Firing Authority Over Mueller