The president’s reasonable proposal addresses a lethal problem: People who are in the business of selling guns can avoid the current requirement to conduct background checks on their buyers by claiming not to be gun dealers. Go to a gun show, for example, and in booths right next to licensed gun dealers whose customers have to undergo background checks, you will see others who operate outside of the rules, selling dozens or hundreds of the same guns each year without background checks.

The steps announced this week will narrow that gap by requiring anyone who sells a significant number of guns or operates like a commercial dealer to get a license and require each buyer to pass a criminal background check. Truly private sales, such as simply selling a gun to a neighbor or a friend, will not be affected. But, based on analysis by the gun-violence-prevention organization I co-founded, millions of firearms transactions that currently happen with no questions asked will be subject to background checks.

The president’s proposal makes another key improvement: It addresses the weakness in the background-check system that authorities say allowed a dangerous man to buy a gun and murder nine innocent people in a Charleston, S.C., church. It does this by making the system more efficient and effective, including by increasing the number of background-check examiners and related staff members by 50 percent and reporting which states do and don’t provide essential background-check records to the FBI.

Other important provisions will require gun dealers to report lost and stolen guns, making it easier for law enforcement to crack down on the illegal gun trade; and will increase investment in gun safety technology and mental-health treatment. These are just common sense.

Almost three years ago, when a minority of senators caved in to their fear of the corporate gun lobby and blocked sensible, bipartisan background-check legislation in Congress, I said that those senators had failed their constituents and, with every preventable gun death, made shame their legacy.

Many of those same senators, along with a lot of other elected officials and some candidates for president, will be quick to haul out the talking points the gun lobbyists in Washington gave them and attack the president’s reasonable action. They will warn of dire consequences and willfully spread misinformation. But the truth is this: These new steps will hurt no one, and they will protect many.

Around mile 32 of the bike ride I did in November, I almost gave up. I’m mostly paralyzed on my right side, and even though I had been training for months, my body was tired and it was hard to keep going. But I remembered my goal. I had a team of friends and supporters with me, so we just kept pedaling together. And then we crossed the finish line.

Reducing the number of Americans murdered or injured by guns is also not easy. It’s a long, hard haul.

But we cannot falter now, and we cannot wait for a Congress in the gun lobby’s grip to prevent any of the 12,000 gun murders that happen in our country every year.