DONALD TRUMP appeared Friday before the National Rifle Association and promised to roll back gun restrictions if elected president. The next day, Hillary Clinton stood before a group of mothers who have lost children or other relatives to gun violence and vowed to fight for stricter gun control. The back-to-back speeches by the presumptive Republican nominee and his likely Democratic opponent signal the prominent role that gun issues may play in the presidential election. That would be a welcome contrast to the recent past, when the critical matter of gun violence — and how to combat it — was missing in action from national election debates.

Ms. Clinton has highlighted her disagreement with Sen. Bernie Sanders (I-Vt.) over gun policy in their primary battle. Traditionally, Democrats running for office tread gingerly on the issue so as not to rile the NRA, but Ms. Clinton seems eager to take on the powerful organization. “Unlike Donald Trump, I will not pander to the gun lobby,” she said Saturday, after the NRA had endorsed Mr. Trump.

The NRA’s earlier-than-normal backing — further evidence of the prominence that gun control promises to have this fall — came despite Mr. Trump’s highly changeable positions on gun laws. In 2000, he backed a ban on assault weapons and longer waiting periods to purchase firearms. After the 2012 slaughter of schoolchildren at Sandy Hook, he lauded the president’s call for gun reform, saying Mr. Obama “spoke for me and every American.”

That is no longer operative, apparently. In his speech to the NRA, Mr. Trump sought to confirm his gun-toting credentials, wrongly depicted Ms. Clinton as wanting to abolish the Second Amendment and vowed to get rid of gun-free school zones. Of course, as tends to happen with Mr. Trump, there was incoherence in his proposed policies, as evident in his remarkable attempt to parse his comments on guns in schools. “I don’t want to have guns in classrooms, although in some cases teachers should have guns in classrooms, frankly, because teachers are, you know, things that are going on in our schools are unbelievable” — that is just part of what he said less than 24 hours after calling for elimination of gun-free school zones.

What should not get lost in trying to make sense of the senseless is how much the nation has lost by avoiding serious debate on this issue for so long. Some 33,000 Americans each year are killed by guns. This year the statistics will include the 5-year-old girl who shot herself over the weekend when she picked up her father’s gun; last year, the 56-year-old man caught in the crossfire when he stopped to get cigarettes at an Elks Lodge in Cincinnati. Gun violence is a public-health crisis. If we actually debate ways to manufacture a gun, say, that a 5-year-old can’t accidentally fire, many lives might be saved.