William Barr, who served as U.S. attorney general during the final two years of the George H.W. Bush administration, is returning to lead the Justice Department. Donald J. Trump has said he will nominate Barr to succeed Matthew Whitaker, the acting AG.

Here, though, is the question I would ask him if I had the authority to ask it of the AG-designate: Will you commit to allowing special counsel Robert Mueller complete his investigation into whether the president’s campaign team colluded with Russians who attacked our electoral system in 2016?

The president has said repeatedly that former Attorney General Jeff Sessions should never have recused himself from the Russia probe, that he should have revealed he would do so before Trump nominated him. Trump saw Sessions’ recusal as a “betrayal” of the president, not understanding that the attorney general swears to uphold the law and does not swear to be loyal to the president. Sessions’ recusal was the deal breaker for Trump.

Meanwhile, Mueller has proceeded at full throttle. He has scored indictments, guilty pleas and is zeroing in on other key players in this investigation.

Barr needs to commit to allowing Mueller to conclude his investigation, which now has gone on for well more than a year.

Mueller is not the partisan hack that Trump accuses him of being. He is a former FBI director and a man of impeccable integrity. He needs to finish the job he has begun.

The next AG, and I’ll assume it will be William Barr, needs to let the special counsel complete his work, file his final report and then let the future take its course.

It is my fervent hope that Republican and Democratic senators who will question the AG nominee are on the same page as well.