The former governor of Maryland Martin O’Malley attempted to kick-start his flagging presidential campaign on Monday by announcing a comprehensive plan to end what he called the “epidemic and sickness of gun violence in the United States”.

As part of his ambition to slash the annual death toll from guns by half within a decade, O’Malley pledged that as president he would repeal a 2005 federal law that immunized firearms manufacturers from being sued when their products were used in crimes. The Protection of Lawful Commerce in Arms Act, heavily touted at the time by the main pro-gun lobby, the National Rifle Association, in effect wiped out liability for gun makers across all 50 states.

The act has been used to protect manufacturers and retailers in several lawsuits. This year, for instance, it was invoked when a judge dismissed a lawsuit in Colorado brought by the parents of one of the 12 victims of the 2012 Aurora cinema shooting who wanted to hold accountable the online sellers of the ammunition used in the massacre.

By promising to repeal the act, O’Malley sought to put clear blue water between his campaign and those of his Democratic presidential rivals. In particular, O’Malley has in his sights Bernie Sanders, the independent US senator from Vermont who has come under criticism for his more relaxed approach to gun control.

Sanders has risen in the past few weeks to hold first place in the Democratic nomination race in recent polls from the early caucus and primary states and is widely seen as Hillary Clinton’s main challenger from the left. Yet his stance on guns, honed in the hunting haven of Vermont, has seen Sanders draw some flak.

In one of his most contentions decisions, he voted in favor of shielding gun makers from lawsuits when the law was passed by Congress 10 years ago.

O’Malley clearly sees this issue as one where he can claim the liberal mantle. Launching his new drive against gun violence in an East Harlem school in New York City, he said of gun manufacturers: “If you have ways to make your guns safer, you have a duty to do that.”

The 2005 law, he said, was an example of the “NRA flexing their political muscle to protect special interests”.

Asked by the Guardian to comment on Sanders’ vote for the legislation, O’Malley declined, saying only: “You can draw your own conclusions.”

With the Democratic nomination battle dominated by the surge of Bernie Sanders and the travails of Hillary Clinton, O’Malley has struggled to make his voice heard. The latest tracking poll from Real Clear Politics puts him nationally on a miniscule 2%, way behind Clinton (44%), Sanders (22%) and even the undeclared vice-president Joe Biden (20%).

The beauty of the gun issue for O’Malley strategists is that it gives him a distinct platform that is close to the hearts of many Democratic party members. It also allows him to point to his record in government.

Over eight years as governor of Maryland, he put in place one of the strongest packages of gun control of any state in the country. He introduced comprehensive background checks, fingerprinting and safety training for all buyers, as well as imposing a ban on assault-style weapons and an upper limit of 10 rounds on the size of magazines.

“Our legislature stood up to the threats of the NRA. We drove down gun violence to 30-year lows over those eight years using commonsense measures,” he said.

The issue of guns also allows O’Malley implicitly to challenge Sanders’ claim to be the liberal standard-bearer. Sanders has come under some criticism for his track record on gun control legislation in which he has voted against several key reforms designed to tighten up the notoriously lax gun laws of the country.

Asked by Jake Tapper of CNN in July to explain why he voted for the manufacturers’ shield law, Sanders replied: “If somebody has a gun and it falls into the hands of a murderer, and that murderer kills somebody with the gun, do you hold the gun manufacturer responsible? Not any more than you would hold a hammer company responsible if somebody beat somebody over the head with a hammer.”

The gun control proposals are one of 15 points that O’Malley has compiled as his presidential manifesto to “rebuild the American dream”. Every year some 32,000 Americans are killed by firearms and about 10,000 children are injured.

“Other nations around the world scratch their heads and wonder why we can’t do anything about gun violence. Well, I believe we can,” O’Malley told a room full of about 30 people, including relatives of people killed in shootings.

He added: “No one piece of legislation will ever do away with gun violence, but we can certainly do better than we are now. When we have an epidemic of this scale that is taking so many lives, we have to ask what would we do if it were Ebola – we would act to close the loopholes.”