This week, as lawmakers in Congress braced themselves for a protracted and impassioned debate over gun control, Democratic governors moved swiftly to push tough new gun laws in response to the school massacre in Newtown, Connecticut. New York Gov. Andrew Cuomo easily shepherded legislation through a divided state legislature to produce the strictest gun laws in the country. Maryland Gov. Martin O'Malley has proposed similarly stringent measures, including a ban on assault weapons, while Colorado Gov. John Hickenlooper has called for universal background checks on all gun sales. 

And what do all three governors have in common (besides a strong desire to reform America's gun laws, of course)? They are all considered possible contenders for the 2016 Democratic presidential nomination.

In Cuomo's case, his White House aspirations are such an open secret that Republicans in New York are explicitly connecting the governor's gun-control efforts to his national political ambitions. "Why are we being bullied into voting on this bill without our proper, responsible due diligence?" asked state Assemblyman Steven Katz. "Solely due to the governor's misguided, egotistic notion that this will advance his presidential aspirations."

O'Malley wasn't spared either. "This looks like crass opportunism from politicians who want gun control," said Maryland House Minority Leader Anthony J. O'Donnell. "The reality is Martin O'Malley is trying to get to the left of Cuomo in New York because he wants to run for president in 2016."

Taking a liberal position on guns would surely boost both men's chances in a Democratic primary. Cuomo, who signed a gay marriage bill into law last year, would solidify his progressive credentials. O'Malley would strengthen his reputation for reducing crime, which he established in his previous job as the mayor of Baltimore. (Sending some liberal hearts aflutter, O'Malley is the reported inspiration for the character Tommy Carcetti in the HBO drama The Wire.) 

The traditional political calculus on guns would warn any ambitious pol from veering too far to the left on such a divisive issue, lest he or she suffer the consequences in the general election. So the alacrity with which Cuomo and others have jumped on the issue suggests that the politics surrounding gun control have altered dramatically, argues Alec MacGillis at The New Republic:

[S]everal high-profile Democrats who've been mentioned as 2016 presidential contenders are betting on a different read of the situation. As they see it, Newtown has truly changed things, making it not just politically feasible to broach new constraints, but perhaps even politically imperative...

The massacre of 20 elementary school students and a half dozen of their educators has indisputably shifted public opinion — in a new Washington Post poll, 52 percent say that Newtown made them more supportive of gun restrictions. The NRA's provocative response has ginned up new members for the organization but not helped with the broader public. And that's even before the families of the victims — and of victims from other recent mass shootings, like the one at a movie theater in Aurora, Colorado — have started to organize themselves as a political force, as we're now starting to see happening. [The New Republic]

Indeed, Hickenlooper's comparatively modest attempts to beef up his state's gun laws may be more indicative of the country's direction than the bills proposed by Cuomo and O'Malley, both of whom hail from reliably blue states. Colorado was a swing state in the presidential election, and proposals for more gun control are bound to meet greater resistance.

And let's not forget the Democratic heavyweights in a potential 2016 primary field. While Secretary of State Hillary Clinton has been on the sidelines due to some health issues, her husband, who lost a lot of political capital by signing a federal ban on assault weapons in 1994, has been a vocal supporter for limiting the sale of high-capacity magazines. "I grew up in a hunting culture, but this is nuts," Bill Clinton recently said. "Why does anybody need a 30-round clip for a gun? Why does anybody need one of those things that carries 100 bullets?"

Then there's Joe Biden, the head of President Obama's gun-control task-force. As Philip Rucker at The Washington Post writes:

By far the biggest platform is being occupied by Biden, who is said to be eyeing a third presidential run in 2016. Three days in a row this week, Biden’s aides have ushered the press into his private meetings with interest groups to hear him make remarks.

Biden spoke passionately not only about the need to reform gun laws — "The public wants us to act," he said — but also about his own history. As a senator, Biden helped author the 1994 assault weapons ban, which expired a decade later, and earned a reputation for being tough on crime. [The Washington Post]

At this point, being a strong gun-control supporter may already be a litmus test for 2016 Democratic nomination.