President Trump, in the wake of the arrest of the suspected assassin of Charlie Kirk, says he expects to go to the funeral in Arizona. No doubt millions will be watching to see whether the president addresses the mood of the country — the anger, the tone of the debate, and a lack of civility. Count us among them, though we confess that we are skeptical that the crime that shocked the nation this week can be laid to the tenor of the political debate.

“There is,” Governor Spencer Cox declared today in Utah, “one person responsible for what happened here.” He was referencing the accused killer, Tyler Robinson. “That person is now in custody,” Mr. Cox added, “and will be held accountable.” The governor, though, went on to call for a de-escalation of the political rhetoric in the country — “an off-ramp,” in his words — and Mr. Trump wasn’t far behind him. 

“All of us have an opportunity right now to do something different,” Mr. Cox went on. He praised the residents of his state for their calm response to the assassination of the conservative activist. “There was no rioting, there was no looting, there were no cars set on fire, there’s no violence,” he said. Instead, “there were vigils and prayers and people coming together to share the humanity.” That, in Mr. Cox’s telling, “is the answer to this.”

Evoking the political violence that erupted the latter 1960s, including the assassinations of the Reverend Martin Luther King Jr. and Senator Robert Kennedy, Mr. Cox asked, “Is this the end of a dark chapter in our history, or the beginning of a darker chapter in our history?” The question resonates amid the divisions in America that were laid bare by the assassination of Kirk, especially as details emerge about the alleged gunman’s motivation.

Bullet casings retrieved from the rifle used to shoot Kirk, authorities say, featured political messages that suggest Mr. Robinson was animated by hostility toward Kirk, who he insinuated was a “fascist,” and the conservative movement. Such phrases vindicate Mr. Trump’s concern that “those on the radical left have compared wonderful Americans like Charlie to Nazis and the world’s worst mass murderers and criminals.” 

Echoing Mr. Cox’s remarks, the House speaker, Mike Johnson, suggests that today’s vitriol is “a common challenge for all of us.” Mr. Trump says he will likely attend Kirk’s funeral, slated for next weekend. If he uses the moment of the obsequies to address the nation, he might find the measured assessments by Messrs. Cox and Johnson provide an opportunity for presidential leadership at a time when America could well use some bipartisan balm.

Mr. Trump seems to grasp the need for this kind of dialing back of the heated talk that is being bandied on both sides of the political debate. Even if the president himself has been known to use harsh language against his political foes, in the aftermath of the shooting he is urging his backers to follow Kirk’s own philosophy. Kirk “was an advocate of nonviolence,” Mr. Trump said. “That’s the way I’d like to see people respond.”