Attorney General William Barr is setting the stage for a Senate brawl on his way out the door with the appointment of U.S. Attorney John Durham to serve as special counsel well beyond the end of the Trump administration.

The fight over Durham, the federal prosecutor probing the origins of the 2016 Russia investigation, will be in full force once President-elect Joe Biden nominates his pick for attorney general.

Senate Republicans say Biden’s nominee to lead the Justice Department should promise not to terminate Durham, who has been investigating whether the Obama administration improperly targeted the Trump campaign in 2016 when the FBI looked into allegations of collusion between the campaign and Russian officials.

Republicans on the Senate Judiciary Committee, which will hold hearings for Biden’s attorney general pick, want a pledge that the nominee will not interfere with Durham’s work.

“I think John Durham’s investigation is very important, and any attorney general who would impede that investigation or who would obstruct justice shouldn’t be confirmed,” said Sen. Ted Cruz (R-Texas), a member of the Judiciary panel.

A special counsel can only be fired by the attorney general for a stated reason such as misconduct, dereliction of duty, incapacity, conflict of interest or violating department policies.

Sen. Josh Hawley (R-Mo.), who also serves on Judiciary, defended the need for Durham’s work to continue after Biden takes office.

“The public deserves to know what is going on here and they deserve to get all of the facts and information,” he said. “The investigation needs to conclude but it needs to be allowed to conclude in a timely fashion.”