The bill passed the Senate in a bipartisan 26-10 vote following a respectful and at times somber six-hour debate Wednesday evening. The House of Representatives then debated the bill and was expected to vote later in the night. Democratic Gov. Dannel P. Malloy has said he would sign it into law.
The legislation adds more than 100 firearms to the state's assault weapons ban and creates what officials have called the nation's first dangerous weapon offender registry as well as eligibility rules for buying ammunition. Some parts of the bill would take effect immediately after Malloy's signature, including background checks for all firearms sales.
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.
"This would put Connecticut right at the top or near the top of the states with the strongest gun laws," Malte said.
Colorado and New York also passed new gun control requirements in the wake of the Newtown shooting, in which a 20-year-old gunman used a military-style semi-automatic rifle to kill 20 first-graders and six educators.
Compared with Connecticut's legislation, which, for example, bans the sale or purchase of ammunition magazines holding more than 10 rounds, New York restricted magazines to seven bullets and gave owners of higher-capacity magazines a year to sell them elsewhere. Colorado banned ammunition magazines that hold more than 15 rounds.
"There are pieces that are stronger in other states, but, in totality, this will be the strongest gun legislation passed in the United States," Betty Gallo, a lobbyist for Connecticut Against Gun Violence, said of the Connecticut bill.
Many senators spoke of balancing the rights of gun owners with addressing the horror of the Sandy Hook shooting. Lawmakers said they received thousands of emails and phone calls urging them to vote for or against the bill, with veteran Sen. Joan Hartley, a Democrat, saying she's never seen a more polarizing issue at the state Capitol.
But Senate Minority Leader John McKinney, R-Fairfield, whose district includes Newtown, said he felt he was representing the interests of the Sandy Hook victims as he cast his vote.
"I stand here as their voice, as their elected representative," he said, reciting the names of the 26 victims at the school.
Gun rights advocates who greatly outnumbered gun control supporters in demonstrations held earlier in the day at the Capitol railed against the proposals as misguided and unconstitutional, occasionally chanting "No! No! No!" and "Read the bill!"
"We want them to write laws that are sensible," said Ron Pariseau, of Pomfret, who was angry he'll be made a felon if he doesn't register his weapons that will no longer be sold in Connecticut. "What they're proposing will not stop anything."
By the time the Senate voted, many of the gun rights advocates had gone home, leaving behind proponents of the bill who applauded when the tally was read.
In the legislature, where Democrats control both houses, leaders waited to unveil gun legislation until they struck a bipartisan deal that they say shows how the parties can work together elsewhere. They touted the package as a comprehensive response to Newtown that also addresses mental health and school security measures, including the creation of a new council to establish school safety standards and the expansion of circumstances when someone's mental history disqualifies him or her from obtaining a gun permit or other gun credentials.
But momentum on federal legislation has stalled in Congress, and President Barack Obama has planned a trip to Connecticut on Monday to step up pressure to pass a bill.
A silent majority in favor of stronger gun control has emerged following the Newtown massacre, Gallo said.
Among the gun control advocates were Dan and Lauren Garrett, of Hamden, wearing green shirts in honor of the Sandy Hook victims. The Garretts traveled to Hartford with their 10-month-old son, Robert, to watch the bill's passage. They said they hope lawmakers will build on the proposal.
"It's just the beginning of this bill. In six months from now, it's going to get stronger and stronger," Dan Garrett said. "I think they're watching us all over the country."
But gun rights advocates and some lawmakers questioned whether the legislation would have done anything to stop Adam Lanza, the gunman who blasted his way into Sandy Hook Elementary. State police say he fired 154 shots with a Bushmaster .223-caliber rifle inside the school, then killed himself with a handgun. He had shot to death his mother, Nancy, before going to the school, and search warrants of the Lanzas' home showed it was packed with weapons and ammunition.
In a state where gun manufacturing dates back to the Revolutionary War, law-abiding gun owners are paying the price for the actions of a deranged young man, said a Republican state senator, Tony Guglielmo.
"The problem is I can't connect the dots between Adam Lanza and the good guys. So 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.