Thoughts and prayers, we are often reminded, only go so far. And politicians’ attention spans are alarmingly short.

On July 31, just three days after four people died in Gilroy, California, and three days before at least 31 more would be killed in El Paso, Texas, and Dayton, Ohio, none of the 10 Democrats on the debate stage in Detroit said a word about gun violence. And none of CNN’s three moderators bothered to ask about what is unquestionably a national nightmare.

The prior night, Don Lemon directed one question about guns to South Bend, Indiana, Mayor Pete Buttigieg. Several other candidates then made brief remarks on the subject, but over the two nights, there was not a syllable about guns from: Elizabeth Warren, Joe Biden, Cory Booker, Julian Castro, Michael Bennet, Kirsten Gillibrand, Kamala Harris, Andrew Yang, Tulsi Gabbard, Jay Inslee, Tim Ryan, John Delaney and Bill de Blasio.

Gun control should be a central issue for Democrats in 2020. Congress might be paralyzed but voters want action. More than 60 percent of Americans, according to Gallup research, favor stricter gun control — above 85 percent among Democrats. Other polls reflect roughly the same percentages.

Over two nights of debating among 20 Democrats in Detroit, the word “health” (as in health care) was spoken 183 times, “Plan” was said 153 times, “tax” 58 times. “Gun” was said just 15 times on night one, and zero times on night two.

Lemon asked Sen. Warren about the related matter of white nationalism. “We need to call out white supremacy for what it is: domestic terrorism,” she said. “And it poses a threat to the United States of America.” She then shifted broadly to “environmental racism, economic racism, criminal justice racism, health care racism.” And, without interruption she went on to outline her plan for “universal, tuition-free college.”

Voters who have been sitting through the seemingly endless presidential campaign that still has nearly 15 months to go should be incensed that Democratic candidates spend so little time addressing gun violence and the scourge of white nationalism. CNN’s moderators should be taken to task for virtually ignoring the issues, while finding time to drill down about such things as lead poisoning in New York City and the drinking water in Flint, Michigan, as important as those topics might be.

Democrats have managed to divide themselves on health care, the main issue that united the party in the 2018 midterms. They have squabbled over decriminalizing illegal immigration. Some have even taken to attacking the record of President Obama. But when it comes to gun control — about which they could come together — they remain relatively quiet on the problem and generally uninspired in finding solutions.

In 2018 Mr. Trump said he favored action on universal background checks, but the next day backed away. The House has passed two bills to deal with it but Senate Majority Leader Mitch McConnell has refused to schedule a vote. Shouldn’t that be a major theme for Democrats?

During the weekend of bloodshed there was, of course, a stampede to the microphones, as members of both parties eagerly spoke up during the media’s brief window of intense interest. On Monday morning President Trump said, “We will never forget.”

For now, gun violence and white nationalism are once again talking points. That’s better than silence, but it’s cheap.

Peter Funt is a writer and speaker. His book, “Cautiously Optimistic,” is available at Amazon.com and CandidCamera.com.