Rep. Carolyn Maloney (D-N.Y.) has long advocated for stricter gun laws. But after her latest effort — a bill she introduced last month that would require gun owners to purchase insurance — the congresswoman now fears for her life.

On Tuesday, Maloney said she'd received three phone calls to her New York office in which someone threatened to kill her if she moved ahead with the bill. She said the calls rattled her so much that she skipped a dinner event that night where she was to present an award.

"They said they were going to kill me," Maloney told the New York Daily News. "I think any member of Congress would be scared after what happened to my good friend Gabby Giffords," she added.

The New York Police Department has confirmed that they are investigating the incidents, and said they've assigned officers to guard Maloney's Manhattan home. 

As is typical of her long fight for tougher gun laws, Maloney wrote in The Huffington Post about the need for better gun control in the aftermath of the Newtown, Conn., shooting. She has since followed up on that plea by introducing three gun bills in as many months this year.

So what is it about the latest bill, introduced at the end of March, that's prompting the death threats?

The measure, called the Firearm Risk Protection Act, would require gun owners to obtain liability insurance as a prerequisite for buying guns, or face a fine of up to $10,000. The bill would not apply to guns already in private ownership. In the same way that other forms of insurance work, the idea behind the bill is that the gun insurance would defray the costs guns pass on to the public; violent crimes — gun crimes included — are estimated to cost taxpayers $3.7 billion every year. And unlike other proposed gun laws, the bill frames the debate in terms of economics, not rights.

John Wasik explains the economic angle of gun-owners insurance at Forbes:

There are numerous precedents in auto, homeowners and business insurance, so there's no 2nd Amendment conflict. Ideally, high-risk households would have to pay more and take more safety measures, so at-risk people wouldn't have easy access to them. Responsible buyers would pay lower premiums for taking gun-safety classes, using gun locks and safes. [Forbes

Opponents of tighter firearm laws, however, view the bill as an unnecessary financial burden on law-abiding gun owners. In an editorial today, The Washington Times called the bill, "legislative harassment," arguing that it would most harm poor people who want a gun for self defense but who can't purchase the accompanying insurance.

Similarly, Chris Cox, executive director of the NRA's Institute for Legislative Action, told The Daily Caller that the bill was, "ridiculous on its face, as it presumes law-abiding gun owners are guilty for merely exercising a fundamental, constitutional right."

Undeterred, Maloney says she plans to move ahead with the bill despite the threats.