The are many measures of how a presidential candidate might respond in a moment of national trauma. To my mind, the standard was set on the night of April 4, 1968, when Robert F. Kennedy learned shortly before he was to speak in Indianapolis’s inner city that the Rev. Martin Luther King Jr. had been assassinated. Indianapolis Mayor Richard Lugar, reportedly fearing an eruption of violence, informed Kennedy’s aides that he could not guarantee the safety of the Democratic presidential contender. But Kennedy went ahead and gave his speech that night at an outdoor rally. He began by informing the crowd of the death of the civil-rights leader. Then, sharing the shock and grief of his audience, Kennedy continued:

Martin Luther King dedicated his life to love and to justice between fellow human beings. He died in the cause of that effort. In this difficult day, in this difficult time for the United States, it’s perhaps well to ask what kind of a nation we are and what direction we want to move in. For those of you who are black—considering the evidence evidently is that there were white people who were responsible—you can be filled with bitterness, and with hatred, and a desire for revenge.

We can move in that direction as a country, in greater polarization—black people amongst blacks, and white amongst whites, filled with hatred toward one another. Or we can make an effort, as Martin Luther King did, to understand, and to comprehend, and replace that violence, that stain of bloodshed that has spread across our land, with an effort to understand, compassion, and love.

For those of you who are black and are tempted to fill with—be filled with hatred and mistrust of the injustice of such an act, against all white people, I would only say that I can also feel in my own heart the same kind of feeling. I had a member of my family killed, but he was killed by a white man.

But we have to make an effort in the United States. We have to make an effort to understand, to get beyond, or go beyond these rather difficult times.

Kennedy did not know all the details regarding Dr. King’s assassination. The candidate was cautious in some of his language. Yet, he delivered a clear and compelling statement that was credited by many for easing tensions and encouraging a sense of connection and solidarity.

One of the great tests for presidential candidates comes when they must respond to unexpected, difficult, shocking, and sometimes terrifying moments that arise during the course of a campaign. It is certainly reasonable to suggest that such a moment came on Friday, when the news was dominated by reports from Colorado Springs, where a police officer and two others were killed after a gunman opened fire at a Planned Parenthood clinic. Today’s circumstances are distinct from those of April, 1968. These are different and perhaps more jaded times. Yet, even if we are all too familiar with reports of mass violence, and in particular violence directed toward providers of abortions and reproductive-health services, President Obama was surely right when he said Saturday morning, “We can’t let it become normal.”

As the six-hour standoff ended in Colorado with the arrest of the alleged shooter, social media were filled with responses to the news of the violence that left nine wounded and renewed concerns about violence directed at clinics. This is an age of instant reaction. And even if there were still many questions that could be asked regarding the motives and actions of the shooter, there were also things that could be said.

Former secretary of state Hillary Clinton, a steady defender of Planned Parenthood, was quick to declare on Twitter: “Today and every day, we #StandWithPP.” Clinton linked her comment to a statement from Vicki Cowart, the president and CEO of Planned Parenthood Rocky Mountains, and to news coverage of the unfolding story.

Clinton’s chief rival for the Democratic nomination, Vermont Senator Bernie Sanders, tweeted Friday evening: “We proudly #StandWithPP of Colorado Springs and the brave law enforcement personnel who fought to protect it.” Later, Sanders would issue a statement saying, “While we still do not know the shooter’s motive, what is clear is that Planned Parenthood has been the subject of vicious and unsubstantiated statements attacking an organization that provides critical health care for millions of Americans. I strongly support Planned Parenthood and the work it is doing and hope people realize that bitter rhetoric can have unintended consequences.”

Former Maryland governor Martin O’Malley, the third Democratic contender, also used the #StandWithPP hashtag when he tweeted Saturday morning: “My thoughts and prayers are with those in Colorado. #StandWithPP.”

But what of the Republican contenders who have had so very much to say against Planned Parenthood? Billionaire Donald Trump, Dr. Ben Carson, and the rest of the conservative crew that is usually jostling to be first and loudest went suddenly silent Friday night. For the most part, they remained silent into Saturday—as least with regard to a violent incident that dominated the national news and kitchen-table discussions.

Twenty-four hours after the shooting began in Colorado Springs, the one major Republican contender who commented was Texas Senator Ted Cruz. On Saturday morning, Cruz tweeted: “Praying for the loved ones of those killed, those injured & first responders who bravely got the situation under control in Colorado Springs.”

Later on Saturday, Ohio Governor John Kasich tweeted: “Senseless violence has brought tragedy to Colorado Springs. I pray for the families in mourning and have hope our nation can heal.”

Aside from Cruz and Kasich, the usually noisy Republicans had very little to say about the Colorado shooting or Planned Parenthood.

Their silence was broadly noted.

“2016 Republican Contenders Silent On Planned Parenthood Shooting,” noted one Saturday morning headline, while another read: “Republican candidates are too busy this morning to denounce attack on Planned Parenthood clinic.”

It’s not as if the Republican candidates had nothing at all to say. Florida Senator Marco Rubio was hawking clothes with his campaign’s logo—“Stay warm this winter with our new cold-weather bundle. Shop now and save!”—and declaring his continued opposition to Obamacare. Trump, the front-runner for the GOP nod, was tweeting polling data and announcements of a Florida rally. He even found time to continue griping about New York Times reporter Serge F. Kovaleski—while at the same time denying that he mocked the appearance of a journalist with a physical disability.

But there were no mentions of the latest attack on a clinic run by Planned Parenthood—an organization that the Republicans have stumbled over one another to condemn with clockwork consistency, an organization that has been a major topic of Republican debates.

There was no presumption that Trump or former CEO Carly Fiorina to rush to declare they were standing in solidarity with a group they have regularly savaged—often with casual disregard for the facts and for the role Planned Parenthood clinics play in providing a wide range of health services.

But was there really no place for an immediate expression of concern for the loss of life? For recognition of the service and sacrifice of a slain law-enforcement officer who happened to be the co-pastor of an evangelical church? For conveying an understanding of the distress experienced by people of all political views in Colorado Springs, and across America?

No one expects opponents of abortion rights to change their position in a circumstance such as this. But it is reasonable to expect a caring response in a traumatic time—even if the immediate response is nothing more than an announcement that the candidate is monitoring troublesome reports of violence leading to multiple deaths in an American city.

People who would be president are usually very quick to express their views. There is nothing wrong with this, as presidents frequently face immediate demands for responses to volatile and unsettling developments. One of the most consistent measures of leadership is found in the response to terror, to frightening news, to evidence that mean things are happening in this land. We can expect this of candidates, even if they do not match the eloquence of Bobby Kennedy when he concluded in April 1968: “What we need in the United States is not division; what we need in the United States is not hatred; what we need in the United States is not violence and lawlessness, but is love, and wisdom, and compassion toward one another, and a feeling of justice toward those who still suffer within our country, whether they be white or whether they be black.”