(This June 21 story corrects "automatic" to "semi-automatic" in sixth paragraph)
By David Morgan and Moira Warburton
WASHINGTON (Reuters) - The U.S. Senate took an initial step toward passing the country's first major gun-control legislation in decades on Tuesday, galvanized by two mass shootings in a nation that has long struggled to curb chronic gun violence.
Senators voted to speed passage of a bipartisan package of measures to toughen federal gun laws. The Senate is expected to vote on the 80-page bill this week before a two-week recess.
The bill unveiled on Tuesday does not go as far as Democrats, including President Joe Biden, had sought. Still, if passed, it would be the most significant action to combat gun violence to emerge from Congress in years.
The legislation includes provisions that would help states keep guns out of the hands of those deemed to be a danger to themselves or others and close the so-called boyfriend loophole by blocking gun sales to those convicted of abusing unmarried intimate partners.
After mass shootings at a New York grocery store and a Texas elementary school that authorities said were committed by teenagers, the legislation would allow states to provide juvenile records to the national background check system for gun purchases.
The bill stops short of raising the age limit from 18 to 21 on purchases of semi-automatic assault-style weapons. The shooters in both Texas and New York were 18-year-olds who used assault-style rifles they bought themselves.
Senate Majority Leader Chuck Schumer said he expected the bill to pass this week, while Senator Chris Murphy, the lead Democrat in talks to craft a legislative deal with Republicans, called it "the most significant piece of anti-gun-violence legislation Congress will have passed in 30 years."
"This is a breakthrough," Murphy said on the Senate floor ahead of the bill's release. "And more importantly, it is a bipartisan breakthrough."
The Republican leader in the Senate, Mitch McConnell, called the legislation "a commonsense package" and pledged his support.
With the 100-seat Senate split evenly between the two parties, the legislation will need support from at least 10 Republicans to pass a procedural hurdle. Fourteen Republicans, including McConnell, joined all 50 Democrats to move toward voting on the legislation.
The biggest gun lobby in the country, the National Rifle Association, said on Twitter that it opposed the legislation because it could be abused to restrict lawful gun purchases. The politically powerful group's statement could affect how many Republicans vote on the measure.
Senator John Cornyn, the lead Republican negotiator in the bipartisan talks, held out hope the legislation would succeed.
"We know there's no such thing as a perfect piece of legislation. We are imperfect human beings. But we have to try, and I believe this bill is a step in the right direction," Cornyn said on the Senate floor.
The bipartisan group has been working on a deal to curb gun violence since a gunman killed 19 children and two teachers at the elementary school in Uvalde, Texas, less than two weeks after 10 people were killed in a racist shooting at the supermarket in Buffalo, New York.
Lawmakers reached agreement on a provision to encourage states to adopt "red flag" laws, in which guns can be temporarily taken away from people who are deemed dangerous. It also provides funding for states that use other forms of intervention to accomplish the same outcome.
The bill also aims to close the boyfriend loophole by allowing authorities to block gun purchases by those convicted of misdemeanor domestic abuse against partners to whom they are not married.
(Reporting by David Morgan; Additional reporting by Moira Warburton and Dan Whitcomb; Editing by Scott Malone, Ross Colvin, Cynthia Osterman, Leslie Adler and Gerry Doyle)