Following hours of respectful and at times sombre debate, the House and the Senate in Connecticut voted in favour of the 139-page bill crafted by leaders from both major parties in the Democratic-controlled General Assembly.
The bill now goes to Democratic Gov. Dannel Malloy, who plans to sign it at noon Thursday.
The state, where gun manufacturing dates back to the war for independence from England, has wrestled with the issue of gun safety since 20-year-old Adam Lanza shot his way into the school with a high-powered rifle legally purchased by his mother, whom he killed as well.
The massacre reignited a national debate on gun control, and Obama has made gun safety one of the defining issues of his second term, which started a month after the shooting.
His proposed gun control measures have largely stalled in Congress, however, and Obama has planned a trip to Connecticut on Monday to increase pressure on lawmakers in Washington.
Obama visited Colorado on Wednesday and repeated his call for universal background checks for gun buyers — a measure that has better chances of winning enough support in Congress than an assault weapons ban or limits on large-capacity ammunition magazines.
Obama's visit was heavy with political symbolism because Colorado recently expanded gun control laws despite being a western, largely rural state where gun ownership is a cherished right. Colorado suffered two of the worst mass shootings in U.S. history — at Columbine school in 1999 and at a movie theatre last year. It has expanded background checks for gun purchases and placed restrictions on ammunition magazines.
Obama said Colorado's action shows "there doesn't have to be a conflict" between keeping citizens safe and protecting the right to bear firearms guaranteed by the U.S. Constitution.
But the powerful National Rifle Association gun lobby maintains that more guns keep people safer and have succeeded in blocking many efforts to impose stricter gun controls.
And several county sheriffs in Colorado have vowed not to enforce the new gun restrictions.
In Connecticut, the new legislation adds more than 100 firearms to the state's assault weapons ban and create what officials have called the nation's first dangerous weapon offender registry.
Connecticut will join states including California, New York, New Jersey and Massachusetts in having the country's strongest gun control laws, said Brian Malte, director of mobilization for the Brady Campaign to Prevent Gun Violence in Washington.
But gun rights advocates and some Connecticut lawmakers questioned whether the legislation would have done anything to stop school gunman Adam Lanza.
Law-abiding gun owners are paying the price for the actions of a deranged young man, said a Republican state senator, Tony Guglielmo.
"I think we need to do something, but I guess we should be doing something that does good, not something that just feels good," he said.
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