Vermont Gov. Phil Scott (R) in Montpelier on March 13. (Christinne Muschi/Reuters)

THE DAY after the Parkland school shooting focused renewed attention on the issue of gun violence, Vermont Gov. Phil Scott (R) reiterated his opposition to any new restrictions on gun ownership. But just 24 hours later, Mr. Scott announced a change of heart. Now he has signed major gun violence prevention legislation. It is a notable step for a state that historically has had some of the weakest gun laws in the country, and another encouraging sign of how the ground is shifting on gun control.

What accounted for Mr. Scott’s about-face was his realization of just how close Vermont came to adding its name to the tragic roster of school shootings. The day after 17 people were gunned down at Marjory Stoneman Douglas High School in Florida in February, police in Vermont arrested an 18-year-old who allegedly plotted a mass murder at Fair Haven Union High School in Rutland County. “Now, you know that I’m generally steady and measured, and I realize this is often viewed as lacking emotion,” Mr. Scott said at a news conference. “But quite honestly, in the aftermath of Florida, this situation in Fair Haven has jolted me. . . . Only by the grace of God — and the courage of a young woman who spoke up — did we avert a horrific outcome.”

Mr. Scott posed the question of whether “we are doing everything we can to protect our kids.” The result was the legislature’s passage of a raft of gun-control measures that includes background checks on all gun sales, a prohibition on bump stocks and the sale of high-capacity magazines, an increase in the minimum age to purchase firearms, new protections for domestic-violence victims and a “red flag” law that allows courts to remove access to weapons from people who pose an imminent danger to themselves or others.

That Mr. Scott is facing reelection in November makes his swivel in support of these gun-control measures all the more noteworthy. He, like Florida Gov. Rick Scott (R), who is making a bid for the Senate, seems to have made the political calculation that crossing the national gun lobby runs less risk than opposing laws supported by the public on gun violence prevention. There is movement in other states to enact gun violence prevention bills; seven states now ban bump stocks, and Maryland is on track to become the eighth state with a red-flag law. So it’s about time for Congress and the White House to ask the question posed by Mr. Scott: Are they doing everything they can to protect our kids?