“We have to make sure that we build for the future so no one else has to go through this,” he said. “And I want to say how grateful I am for your leadership. You are making the world a better place and hopefully we don't have to have that many more meetings like this one.”

Since entering the Democratic presidential primary last month, Bloomberg has been amplifying his gun control record as he seeks to win over a party that hasn’t settled on a frontrunner. Gun control is a popular issue with the left flank of the party that is otherwise distrustful of the former New York City mayor’s vast wealth — an estimated $54.7 billion — and routine financial support of Republicans over the years .

On Thursday, he leaned heavily into that idea, casting himself as one of the pioneering champions of common-sense gun reform.

“When I started working on gun violence 15 years ago, neither party — Republicans or the Democrats — were particularly interested interested in the issue,” he told the audience.

Gun control activists gather outside the Supreme Court on Dec. 2. | J. Scott Applewhite/AP Photo

While he argued that he has a track record for tackling gun reform, Bloomberg also vowed to keep up his fight regardless of how his presidential bid turned out.

“My agenda is not some johnny-come-lately list of borrowed ideas,“ he said. “This is part of my life‘s work, and I‘m just telling you I will get this done whether I get elected or not.“

Bloomberg’s plan calls for a background check system that entails permits for all new gun buyers, police notification when owners have been prohibited from holding firearms and a crackdown on unlicensed sellers at gun shows or online, according to campaign officials. As mayor in 2009, Bloomberg oversaw a sting operation at gun shows around the country and turned over illegally-bought firearms to federal authorities.

His team said his proposed law would carve out exceptions for law enforcement officials, hunting and self-defense, and noted 21 states and Washington, D.C. already have similar measures in place.

Bloomberg is also calling for a “red flag screening” to block people who pose a danger from getting permitted to own a firearm. Issuers would have to review histories of domestic violence and other risks.

In anticipation of any backlash to his permitting proposal, a contentious issue among gun rights advocates, Bloomberg came ready with a comparison of the issue to voting rights.

“Now I know critics will say that Americans shouldn’t need a permit to exercise their constitutional rights. But voting is a constitutional right, and we require people to register to protect the rights of all citizens, and this exactly the same idea,” he argued, “because a criminal with a gun can destroy our right to life, liberty and the pursuit of happiness.”

And his plan demands that guns not be sold before background checks are complete, a policy his team said could have prevented 15,000 sales to people prohibited from owning a gun over five years. The “Charleston loophole,” which Democrats have already tried to end , reportedly enabled shooter Dylann Roof to buy a gun in 2015 and kill nine people in a Charleston, S.C., church.

The issue of gun control has long proven a hurdle for Democrats.

President Obama described his failure to secure similar measures in the wake of the Sandy Hook school shooting as one of his greatest regrets, telling BBC in 2015 it was "the one area where I feel that I've been most frustrated and most stymied."

Bloomberg suggested he had the chops to unite a divided Congress, demanding to know “what‘s partisan about stopping carnage,“ emphasizing that he would actually “do something“ about gun violence, no doubt a nod to the number of times gun legislation has stalled in Congress. “The movement we created gets things done,“ he declared.

A spokesman said Bloomberg “is the only candidate in the race who has taken on the NRA and won, time and again,” referring to his personal expenditure of several hundred million dollars on the issue. In 2018, Bloomberg invested $112 million on 24 political candidates who supported gun control measures and won 21 of those races.

“He’s passed gun laws in states across the country that have saved lives, including winning in states with Republican control,” the spokesman, Marc La Vorgna, said in response to how Bloomberg intends to build bipartisan support for his platform. “He has shown he knows how to break through and deliver smart gun laws and will do the same as president.”

Some proposals that can be achieved through executive action include closing the “boyfriend loophole” for physically abusive domestic partners , appointing a White House czar to oversee the issue and setting up a task force.

Prior to his announcement Thursday, Bloomberg received an endorsement from Colorado state Rep. Tom Sullivan, whose son was killed in the Aurora theater shooting, and Pastor Marlon Saunders, whose church hosted Thursday‘s town hall.

Bloomberg's candidacy has already drawn the ire of an old and politically important foe.

“Mike Bloomberg gave Everytown for ‘Gun Safety’ $38M last year – 55% of their revenue. That means that a majority of their budget comes from just ONE BILLIONAIRE. In contrast, the bulk of NRA revenue comes from millions of hard-working Americans. #MicDrop ,” the NRA tweeted about the ex-mayor's gun control organization on Nov. 26.

A day later the organization tweeted, “Michael Bloomberg’s bought and paid for Virginia legislators have wasted no time introducing legislation that would make Virginia's gun laws worse than New York. First up: a total ban on commonly-owned semi-auto firearms and common firearm parts.”

But Bloomberg did not shrink away Thursday, declaring the gun rights lobby a “shell” of what it once was.

He also took aim at President Donald Trump, accusing him of bowing “down to the extremists who run the NRA.”

“Donald Trump seems to accept this violence and pain, and he and the NRA leaders say there isn’t anything we can do about it — and every time I go to another funeral, I think ‘My God, there has to be something we can do about it,’” he said. “I don‘t accept that kids being murdered at school is something we should be used to.”

Caitlin Oprysko contributed to this report.