PORT WASHINGTON, N.Y. – In a sign of the Democratic presidential race’s escalating negativity ahead of the New York primary, Hillary Clinton staged a campaign event here Monday centered entirely on gun control to drive home a sharp contrast with rival Bernie Sanders.

Clinton convened a round table-style discussion in this Long Island suburb where she, along with the local congressman, Rep. Steve Israel (D), and gun-safety advocates hammered Sanders, a senator from Vermont, for his spotty voting record on gun control.

“When challenged on his gun stances, he frequently says: ‘Well, I represent Vermont. It’s a small, rural state,’ ” Clinton said of Sanders.

“Here’s what I want you to know: Most of the guns that are used in crimes and violence and killings in New York come from out of state. The state that has the highest per-capita number of those guns that end up committing crime in New York come from Vermont,” Clinton said, eliciting gasps from the audience of a couple hundred. “So this is not, ‘Oh, no, I live in a rural state. We don’t have any of these problems.’ ”

Many more guns recovered in New York originate from other states like Florida and Pennsylvania, according to a 2014 study by the U.S. Bureau of Alcohol, Tobacco and Firearms. But because of Vermont’s relatively small population, the state ranks highest on a per-capita list.

In a statement, the Sanders campaign quoted Vermont's Gov. Peter Shumlin, who has endorsed Clinton, to push back on the suggestion that Vermont is to blame for New York's gun violence problem.

“I don’t know why Secretary Clinton would be so critical of the governor of Vermont who strongly supports her candidacy," said Sanders spokesman Michael Briggs. "What Gov. Shumlin recently said is true: ‘It is campaign season, therefore, things are sometimes said by all the candidates that sometimes aren't entirely accurate. I would just say this, I think you'd have a hard time convincing Vermonters that New York's crime problems are coming from Vermont.’”

One of the advocates who shared the stage with Clinton was Sandy Phillips, whose daughter was killed in the 2012 movie theater massacre in Aurora, Colo. She spoke movingly about her path to advocacy on the issue and then criticized Sanders.

“We made a call to Bernie Sanders. It did not go well, which is why I’m here today,” Phillips said. She called Clinton “Madam President.”

For months now, Clinton and her allies have attacked Sanders on the issue of guns — in particular over his Senate vote to give immunity to gun manufacturers and sellers.

Israel, a Clinton supporter, said the issue resonates strongly in the New York metropolitan area. In his remarks introducing Clinton, Israel slammed Sanders repeatedly and said, “For families on Long Island, this is one of the most critical issues and vivid contrasts that we have.”

Later, Israel told reporters: “You couldn’t have a more vivid contrast between Hillary Clinton as a senator, a first lady and a future president who has consistently supported the safety of families from gun violence versus Senator Sanders, who as a congressman and senator has consistently supported the gun lobby. This is a line of demarcation.”