Although the debate over stemming gun violence after the massacre in Newtown, Conn., is breaking down mostly along partisan lines in the nation's statehouses -- with several Democratic governors calling for stricter gun laws as most Republicans urge tighter security or revamped mental-health policies -- the handful of exceptions show the political and geographical complexities of the issue.

More than a dozen governors invoked the Newtown school shootings as they opened their legislative sessions in recent weeks with state-of-the-state addresses, and most have weighed in on the shooting in other forums.

Several Democratic governors, mainly along the East Coast, are calling for banning some semiautomatic weapons or large-capacity magazines, while several Republican governors have urged other measures, noting their opposition to more restrictive gun laws. But the state-level debate has not always followed party lines.

Gov. Chris Christie of New Jersey, a Republican who is mentioned as a possible presidential candidate, recently noted that he had long supported his state's existing laws, which he described as "some of the toughest gun control measures in place in the country."

Gov. Mark Dayton of Minnesota was quoted after the shooting as saying that his "reading of the Constitution is that it provides a complete permission for any law-abiding citizen to possess firearms, whichever ones he or she chooses, and the ammunition to go with that." And another Democrat, Gov. Mike Beebe of Arkansas, is likely to sign a bill working its way through the state's GOP-led Legislature, which he was neutral on, that would allow people to bring concealed handguns to churches that choose to allow them.

But in many states, the contours of the debate are following familiar party lines. Democratic governors in Colorado, Connecticut, Delaware, Maryland and Massachusetts are among those calling for stricter gun laws, and Gov. Andrew M. Cuomo of New York has already won the passage of the sweeping gun measures he sought after the shooting at Sandy Hook Elementary School in Newtown. Many Republican governors, meanwhile, are making it clear that they oppose new restrictions on guns.

As Washington debates President Obama's call for stricter federal gun laws, the state-level debate is unfolding at an unusually partisan moment in statehouses. Republicans have the upper hand, holding the governor's office and legislative majorities in 24 states, while the Democrats control both the executive and legislative branches in just 13 states, including Minnesota.

Some Democratic governors have said they are hoping for a federal law that would apply to the whole nation. Gov. Peter Shumlin of Vermont, chairman of the Democratic Governors Association, who was endorsed last year by the National Rifle Association Political Victory Fund, has opposed taking action on gun laws at the state level but said he supports Obama's recommendations.

And Connecticut Gov. Dannel Malloy, a Democrat who has said he would pursue gun control, school safety and mental health measures in response to the shooting that killed 20 first-graders and six educators in his state, said those issues must be addressed at the national level as well.