Mark Kelly, the husband of the former US Congress member Gabby Giffords who was shot in the head in the 2011 Tucson shooting, has called on the leadership of the National Rifle Association to step aside and allow a new generation of more moderate NRA chiefs to emerge.

Kelly has thrown down the gauntlet to Wayne LaPierre, the NRA's combative chief executive, on the opening day of the gun lobby's annual convention in Houston, Texas. Writing in the Houston Chronicle, he accuses LaPierre and the rest of the NRA's leadership of turning their back on the traditional values of the association in a simple drive for profit.

"LaPierre and the gun manufacturers he represents exploit people's fears," Kelly writes. "In return gun manufacturers gave LaPierre and the NRA tens of millions of dollars last year alone - and he spent almost $1 million of it on his own salary."

Kelly's broadside comes at a critical juncture for the NRA, the most powerful gun lobby in America that has led the resistance to President Obama's attempts to tighten gun controls in the wake of the Newtown school tragedy. LaPierre has stridently opposed Obama's main proposal - the extension of FBI background checks on purchasers of all gun sales, not just those at gun shops as at present.

The provision fell in the US senate last month when its supporters failed to achieve the 60 votes needed to pass the chamber. The NRA was instrumental in cajoling 46 senators, including five Democrats, to vote against the gun safety provision, warning that the bill would create a national registry of gun ownership as the first step towards confiscation of weapons even though the draft legislation expressly banned such a registry.

The NRA expects about 70,000 of its more than 4 million members to pass through the George R Brown convention center in downtown Houston over the next three days. It will be the first time the gun lobby has convened its membership since the December disaster in Sandy Hook elementary school, in which 20 young children died at the hands of a lone shooter wielding a military style semi-automatic rifle.

The manufacturer of the AR-15 rifle used in the Sandy Hook massacre, Bushmaster Firearms International, will be exhibiting in booth 3834 of the NRA convention. It will be one of 500 weapons companies displaying their products over 400,000 sq ft of hall space.

Those like Kelly looking for a change in tone or a sense of reflection on the part of the NRA in the wake of Newtown are likely to be disappointed. The main events of the convention kick off on Friday lunchtime with an opening speech by Sarah Palin, who likes to flaunt her moose-hunting skills, and end on Saturday night with a "stand and fight rally" headlined by Glenn Beck.

Other speakers include Ted Cruz, the Texas senator who played a key role in rallying Republicans to force down the background check reform by threatening to filibuster it.

But the uniformly hardline nature of the speakers and the convention programme papers over major cracks within the NRA and within the wider American population. Take Houston, the host city of the NRA convention that prides itself in being gun-friendly.

An annual survey of the opinions of Houston residents by Rice University this year found that 89% were in favour of universal criminal background checks on all gun sales - in tune with national polls. Almost half of the city's population wanted to see a revived federal ban on semi-automatic assault weapons - another proposal that was resoundingly defeated in the US senate.

Kelly, who with Giffords has set up a group called Americans for Responsible Solutions to campaign for a reduction in gun violence, points out in his Houston Chronicle article that LaPierre himself supported universal background checks as recently as 1999. In the aftermath of the Columbine school shooting, the NRA chief told Congress that "we think it's reasonable to provide mandatory instant criminal background checks for every sale at every gun show, no loopholes anywhere for anyone".

But in recent years he has opposed extending FBI monitoring to gun shows and to online sales, that account for 40% of all gun transactions yet are unregulated, on the grounds that it is a secret attempt by the Obama administration to steal law-abiding Americans' guns. In that position he is increasingly out of step with his own NRA members, with polls showing that 74% of them support universal checks.