Rich and powerful, it holds Congress in its sway. But after the murder of 20 young children in Newtown, Connecticut, can the gun lobby still hold out against more stringent controls?

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It has more than four million members and rates every member of Congress according to their attitudes and voting record on gun laws. The National Rifle Association, America's most powerful gun lobby group, spent almost $12m dollars in the last election on negative ads targeting candidates who favour gun controls.

For decades it has successfully campaigned for an end to the assault weapon ban, brought in under the first Clinton administration, which expired 10 years later. Laws allowing people to bring guns into their workplace are now in force across 17 states.

"Stand your ground" laws are on the statute books in more than 20 states, allowing people the right to shoot first in defence of themselves or their property. Illinois, which was the last state to ban concealed weapons, had that law struck down last week.

Little wonder, perhaps, that despite a series of mass shootings which shocked and revulsed the nation even before the tragedy at Sandy Hook elementary school, Adam Gottlieb of the Second Amendment Foundation declared: "We end 2012 with firearms civil rights in the strongest position they have enjoyed in generations. We intend to improve all that in the year ahead."

But has the very nature of that horrific massacre, the slaughter of so many young children which reduced a president to tears and broke America's heart, managed to change the parameters of the debate?

We end 2012 with firearms civil rights in the strongest position they have enjoyed in generations. Adam Gottlieb, Second Amendment Foundation

Certainly, pro-gun organisations have been uncharacteristically silent since the shooting. The NRA, which on Thursday had posted a notice on Facebook boasting of it's 1.7m "likes", has now taken down its entire Facebook page and suspended all activity on Twitter.

Another leading gun lobby group, the National Shooting Sports Federation, has its headquarters in Newtown itself, right across the highway from the elementary school.

Earlier this year, the Atlantic reports, the NSSF fought hard to stop the town's authorities from bringing in more stringent restrictions on gun ownership and shooting, arguing that swimming was far more dangerous. Since Friday, it has been silent.

Clamour for change

Leading politicians have clamoured for change. Those who are famously anti-gun, like Senator Dianne Feinstein, author of that original assault weapons ban, said she would be putting forward a bill calling for its renewal on day one of the new Congress.

New York Mayor Michael Bloomberg took to the Sunday morning talk shows to argue that the legendary power of the gun lobby, and its power to destroy political careers, had been grossly overestimated.

"If Congress wasn't so afraid of the NRA - and I can show you that they have no reason to be - but if they were to stand up and do what was right for the American public, we'd all be a lot better off."

Politicians have been loathe to wade into the controversial issue of gun laws: an issue that sharply divides the nation, and a debate that could risk alienating those white, blue-collar voters who could prove so key to their electoral fortunes.

Democrats who lost out heavily in the mid-terms of 1994 attributed many of those losses to their support for the Brady bill a year earlier: at the local level, many champions of stricter controls have fallen victim to their cause.

America is a country of 300m guns, while 4 million new ones come onto the market every year. 40 per cent of all guns sold legally are sold without any need for a federal background check.

In October, during one of the presidential debates, Barack Obama declared himself a supporter of the right to bear arms. "We're a nation that believes in the second amendment, and I believe in the second amendment. We've got a long tradition of hunting and sportsmen and preople who want to make sure they can protect themselves."

Crossing a line

On Monday the White House spokesman Jay Carney would not comment on any specific policy proposals, saying that more gun regulation was part, but by no means all of the solutuion.

But, even though emotions are still too raw, the shock too immediate, for the president to speak of legal changes, the groundswell of support for new legislation is moving beyond the usual constituency.

Senator Joe Lieberman has called for all sides to come together on the issue in a national commission: "The strongest conceivable gun laws won't stop all acts of violence", he said, but insisted that the stronger the gun control laws were, the fewer acts of violence, including mass violence, would happen.

And then came a statement from West Virginia Senator Joe Manchin, as pro-NRA as they come, who infamously starred in a campaign ad two years ago shooting through a bill he opposed with a rifle.

He said it was now time to move beyond mere dialogue towards "a sensible, reasonable approach to fixing it". All ideas, he went on, should be on the table.

Perhaps Mayor Bloomberg has a point. According to the Sunlight Foundation, which publishes details of political donations by leading lobby groups, the NRA's political fund did not get much return on its investment in the last election.

It spent a total of $11,787,523 in 2012, but less than 1 per cent of that money actually went on achieving the desired result. Only six of the candidates it opposed ended up being defeated.

And for President Obama, perhaps a time when he has never had so little to lose: there is no re-election to worry about, while the voters of Ohio and Pennsylvania and Virginia have already given him their support.

Conflicted minds

In that presidential debate back in October, he talked vaguely about an assault weapons ban, and how the issue of hand guns could also be brought into the conversation. It was well short of the forthright opinion he held in 1996, when he said he would support state legislation to ban the "manufacture, sale and possession of handguns".

Public opinion has always remained conflicted. The horror over other mass shootings has been mixed with a widespread feeling that random acts of violence by disturbed individuals would be unaffected by new laws.

This time, though, in the immediate aftermath of the Newtown tragedy, things seem different, with one new poll showing 52 per cent think the shooting reveals "broader problems in American society", compared to 43 per cent who disagree.

An ABC/Washington Post survey found more than half of Ameicans now favour stricter gun laws, the highest level for five years.

So will Obama's call for meaningful action on guns tun into concrete change? There are the worries about the fiscal cliff, talk of new laws on immigration, and the state of the union address is but weeks away.

Given there now appears to be the will, the grief of a bloodied nation could prove the making of his political legacy.

Felicity Spector writes about US politics for Channel 4 News