The gun lobby helped elect Donald Trump to the White House. Now it is looking to the new U.S. President to achieve a long-sought goal: making it easier to carry concealed weapons nationwide.

The looming legislative clash will reopen one of the most divisive subjects in American politics, pitting gun-rights groups against law-enforcement officials in major cities, together with organizations that favour stricter regulations on guns.

The fight will also demonstrate the depth of Mr. Trump's commitment to the gun-rights cause. On Friday, he is expected to become the first president since Ronald Reagan to address an annual gathering of the National Rifle Association, the United States's most powerful group representing gun owners and the gun industry. The NRA was an early and fervent supporter of Mr. Trump's campaign.

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Already Mr. Trump has eliminated several firearm restrictions put in place by the Obama administration, including one aimed at keeping people with mental disabilities from buying guns. But gun-rights groups and their allies in the U.S. Congress are targeting more ambitious policy change.

Republican legislators have introduced bills in the Senate and the House of Representatives that would require states to recognize permits to carry concealed weapons that are issued by other states, a concept known as reciprocity. Gun-rights groups say that gun owners should not have to worry about navigating a confusing patchwork of regulations when they travel from one state to another, risking legal jeopardy or fines.

Gun-control proponents say that the measure is a dangerous step that prevents states and cities from deciding for themselves who can carry hidden loaded weapons. In New York City, for instance, stringent rules governing who can receive such permits have limited their number to only a few thousand. In the state of Florida, by comparison, more than 1.7 million people hold concealed-carry permits. Another 12 states generally do not require a permit at all to carry a concealed weapon.

"The same laws that apply to rural areas should not apply to urban areas with millions of people and thousands of police," said Cyrus Vance Jr., the Manhattan district attorney, earlier this month. "We will not tolerate subways packed with pistols or shootouts in Times Square."

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The bills under consideration differ slightly, but in the version introduced in the House, residents of states where no permits are required would carry that privilege with them wherever they travel in the United States, said Laura Cutilletta, managing attorney at the Law Center to Prevent Gun Violence. "That makes it very hard to know who should have a permit and who shouldn't, and whether someone is lawfully carrying or not."

Gays Against Guns, a new activist group formed last year in the wake of the massacre at the Pulse nightclub in Orlando, is making the fight against concealed-carry reciprocity its first major initiative. This measure "literally keeps me up at night," said Kevin Gotkin, an organizer with the group. It is a "major tool to achieve the [gun lobby's] dream of having guns everywhere."

Gun-rights groups say they want to make a concealed-carry permit akin to a driver's licence, which is recognized wherever someone travels. "Law-abiding citizens should be able to exercise their fundamental right to self-defence while travelling across state lines," said Chris Cox, executive director of the NRA's lobbying arm, in a statement last month. The group did not respond to further requests for comment.

Unlike driver's licences, however, the qualifications for receiving a concealed-carry permit differ considerably from state to state. Some states require firearm training and a certain number of hours of instruction while others do not; some states disqualify people convicted of domestic violence while others do not. Some states – notably Utah and Florida – also issue permits to non-residents.

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The NRA and like-minded groups stood little chance of implementing their vision of nationwide concealed-carry reciprocity during the eight years of Barack Obama's administration, thanks to the high likelihood that the president would have vetoed such a measure (a concealed-carry reciprocity measure passed the House in 2011 but went no further).

Now, with the White House and both houses of Congress in Republican hands, the prospect of success is higher. Mr. Trump himself has a permit to carry a concealed weapon, something he described during the campaign as a "right, not a privilege."

The measure under consideration in the House already has 188 co-sponsors, while a similar bill in the Senate has 36 co-sponsors. The main challenge for Republicans will arise in the Senate, where Democrats could use the procedural hurdle of a filibuster to block a vote. Overcoming that obstacle would require Republicans to persuade eight Democrats to cross the aisle, a tough – but not impossible – task.

Mr. Gotkin of Gays Against Guns said that he expects possible votes on the measure before Congress breaks for its summer recess. In the meantime, his group is planning to ratchet up its protests and advocacy to drive voters to contact their elected representatives. "Once people really take a look at this, there's going to be a major outcry," he predicted.