Whether Congress passes new gun-control laws after the back-to-back attacks in El Paso and Dayton, Ohio, probably comes down to whether President Trump decides to push Republicans in Congress to vote for such legislation. And whether Trump decides to push Republicans seems probably to come down to what his supporters think. Trump has never been one to cross his base — like, ever — and the New York Times reports he’s going to commission a poll of his supporters see what they say.

We don’t know how thorough his poll will be, but there is evidence from a recent high-quality public poll that he could find significant support from his base to push for new gun-control laws.

Fox News surveyed voters immediately after the El Paso and Dayton shootings, and the numbers show the momentum is there among Trump’s base to push for gun-control legislation on nearly every aspect of the debate, including: what Trump voters most fear (mass shootings over a terrorist threat), why they think the problem exists (access to guns is up there with concern over lack of services for mentally ill people), and what to do about it (there is measurable support for expanding background checks and red-flag laws).

That’s not to say this is an easy lift for Trump. Gun rights is still a heavily partisan issue, and one where the grass-roots passion has historically been against any laws restricting access to guns. I was just talking with a Republican strategist who says that whenever gun-control legislation comes up in Congress, Republican lawmakers’ offices get flooded with phone calls and emails of constituents who vehemently oppose it. The National Rifle Association, beleaguered as it is, is still talking directly to Trump, telling him not to support any of this.

But still, if Trump wanted to build support for this — as he’s suggested he might do — he won’t be starting from zero.

Let’s dig a little deeper into the numbers to understand why.

First, Fox asked an open-ended question of why mass shootings happen more often in the United States than in other countries. A plurality of all voters said it was because of lack of gun laws.

Among Trump voters, that’s reversed — but 18 percent still offered up a lack of gun laws as the problem, without being prompted.

Fox also asked what people think is the bigger threat, a mass shooting by an American citizen or an international terrorist threat. There, Trump voters said a mass shooting scares them more.

That’s significant given that Trump campaigned in 2016 on a ban of travelers from majority-Muslim countries aimed at stopping terrorists, and every time he mentioned guns, it was to call for expanding or protecting Americans’ expanded access to them.

As for why there are so many mass shootings in America compared to other nations, 61 percent of Trump voters would blame easy access to guns “a great deal or some.” Though more blame lack of services for mentally ill people (88 percent “a great deal or some”), this is yet another question that strongly suggests Trump’s base is open to a conversation about new gun-control laws to stop mass shootings.

In fact, a significant majority of Trump voters support the two likeliest options circulating around Washington right now: expanding background checks to make them universal for all gun buyers rather than just federally licensed gun dealers, and red-flag laws to allow a judge to take away a person’s firearms if they are deemed a violent threat.

Expanding background checks has generally polled extremely high among Americans; for years, it’s been polling in the 90s.

But support for background checks on the right starts to break off once you ask who, specifically, might have to undergo background checks. A bill passed by the Democratic-controlled House of Representatives in February includes background checks for private sales in gun shows and all but a few exceptions for family-member-to-family-member sales. This Fox poll question was notable in that it asked who supports background checks for “all” gun buyers, “including those buying at gun shows and private sales.” That’s an expansive theoretical background check proposal, and it still got 90 percent among Trump voters.

And while public support for gun-control laws tends to peak immediately after mass shootings, these numbers among Trump voters don’t seem to be an anomaly. A Post-ABC News poll taken in April 2018, more than a year ago, found that 77 percent of Trump voters supported red-flag laws and over 6 in 10 Trump voters supported them “strongly.”

One of Trump’s closest allies in Congress, Sen. Lindsey O. Graham (R-S.C.), is advocating bipartisan legislation that would encourage states to set up their own versions of such laws.

There are still plenty of partisan fault lines in the gun debate. But to the extent we’ve reached an inflection point, and to the extent Trump wants to use his political capital to do something about it, we have early numbers that suggest his base not be entirely opposed to it.

Scott Clement contributed to this story.