There is no question that the American public needs to hear from Robert Mueller, the special counsel, directly.

Mr. Mueller delivered his 448-page report on his investigation into Russian election interference to Attorney General William Barr in late March. That did little to clarify his findings.

Mr. Barr, for his part, has repeatedly tried to muddy Mr. Mueller’s conclusions. He quickly released a summary of the special counsel’s report — prompting Mr. Mueller to take the extraordinary step of writing the attorney general to make clear his displeasure at how Mr. Barr had spun his team’s nearly two years of work. Mr. Barr’s actions since then, including his performance before the Senate Judiciary Committee last week, have hardly clarified matters.

Mr. Mueller has tentatively agreed to testify before Congress on May 15. That led President Trump, who has said he could have long ago fired the special counsel, to protest on Twitter on Sunday that Mr. Mueller “should not testify,” a reversal from his position just days earlier, when he said it would be up to Mr. Barr.