If Wednesday’s first gubernatorial debate set the tone for the campaign to come, and we believe it did, the gun law passed after the mass killing at the Sandy Hook Elementary School in Newtown will play a significant role in determining a winner.

Incumbent Gov. Dannel P. Malloy stood strongly by the bill he signed into law in 2013. It imposed universal background checks, a ban on sales of ammunition magazines with 10 or more rounds, and a broadening of the definition of outlawed “assault weapons.”

The law allowed residents who possessed the now outlawed magazines and weapons to keep them, but required registration. Those who failed to do so are now in violation.

The Day editorially backed the law from the start. It’s working. As the governor noted, the tougher background checks stopped more than 200 people from buying guns, including some subject to restraint orders for domestic violence. It has very likely saved lives.

As for outlawing assault weapons and high-capacity magazines, they were designed for combat and have no role in hunting.

Gov. Malloy’s clear-cut position on where he stands was admirable.

“If a repeal comes to me, I will never sign (it),” he told the debate audience at Norwich Free Academy.

But we also recognize that the governor is making a political calculation.

Second Amendment advocates are passionate in their opposition to the bill, but they are a minority, and the governor recognizes he will never get their vote for re-election. His focus is on the majority of people who support the gun law.

A May 2014 Quinnipiac University poll found 56 percent of voters support the stricter gun law, including 54 percent of independents, and the numbers are consistent across all age groups.

The Republican challenger, businessman and former ambassador Tom Foley, who paid little attention to the Second Amendment when he lost to Malloy by 6,404 votes in 2010, was far more nuanced — some might say slippery — on the issue.

We might be tempted to criticize him for failing to take a strong stand, but recognize that he, too, is making a political calculation.

Mr. Foley wants to tap the passion of those Second Amendment advocates but not alienate too many supporters of the law. This led to his less than Churchillian stance on the matter.

“If the legislature handed me a repeal … I would sign it. That is not saying I would seek repeal,” Mr. Foley told the NFA audience.

The Republican candidate did say he would seek to change that aspect of the law that makes “felons” out of citizens who owned weapons now classified as illegal, but failed to register them. In fact, failure to register is only a misdemeanor.

 “That aspect of the law, I would change,” Mr. Foley said.

He will need to spell out, however, how leniency on registration is accomplished without undermining the law. In addition, Second Amendment advocates might see any attempt to amend the law, rather than repeal it, as apostasy.

Making things more uncomfortable for Mr. Foley is that Joe Visconti, a Second Amendment zealot, has qualified for the ballot. You can find Mr. Visconti in a campaign video that features him riding in a convertible festooned with guns and concludes with him sliding his jacket aside to show he’s carrying. Mr. Visconti says he would introduce a repeal bill upon his election.

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If he remains middling about repeal of the gun law, Mr. Foley risks losing critical votes to Mr. Visconti.  If he goes all in against it, he could lose moderates who support the law.

Which is why Gov. Malloy said Wednesday, “If that fight (defending the gun law) is what this (election) is about, then let it be joined.”

And it is why Mr. Foley would rather not join it, but might have to.