In the wake of a school shooting in Texas that left 19 children and two adults dead, President Biden asked: "When are we going to stand up to the gun lobby?"
The National Rifle Association (NRA), the largest gun-owners' organisation in the US, lobbies against gun-control laws. It is holding its annual meeting in Texas, from Friday 27 to Sunday 29 May.
What has the NRA said about the Texas shooting?
The NRA condemned the shooting in Uvalde, calling it a "horrific and evil crime" and "the act of a lone, deranged criminal". It said it would "redouble our commitment to making our schools secure."
There have been calls for the NRA to cancel its event, which is being headlined by former president Donald Trump in Houston - about a four-hour drive from Ulvade.
Texas senator Ted Cruz, who recently rejected gun control as a way of stopping school shootings, is also due to speak.
What is the NRA?
NRA stands for National Rifle Association. It was founded in 1871 by two US Civil War veterans as a recreational group designed to "promote and encourage rifle shooting on a scientific basis".
In 1975, it formed a lobbying arm, the Institute for Legislative Action, to influence government policy. And in 1977 it formed its own Political Action Committee (PAC), to channel funds to legislators.
The NRA is now among the most powerful special interest lobby groups in the US, with a substantial budget to influence members of Congress on gun policy. It is run by executive vice-president Wayne LaPierre.
Prosecutors are fighting a legal battle to dissolve the organisation, over allegations that senior leadership misused a charity fund, using it for lavish personal spending. The NRA described the lawsuit as a "baseless, premeditated attack".
How big is its budget?
In 2020, the NRA spent about $250m (£200m) - far more than all the country's gun control advocacy groups put together.
But the NRA has a much larger membership than any of those groups and uses its funds for things such as gun ranges and educational programmes.
The NRA officially spends about $3m per year to influence gun policy.
However, that is only the recorded contributions to lawmakers, and considerable sums are spent elsewhere via PACs and independent contributions - funds which are difficult to track.
The NRA also has considerable indirect influence via its membership, many of whom will vote one way or another based on this single issue.
It grades members of Congress from A to F on their perceived friendliness to gun rights. Those ratings can have a serious effect on poll numbers and even cost pro-gun control candidates a seat.
How big is the NRA?
Estimates of the NRA's membership vary widely. The association claimed that membership surged to close to five million in response to the mass shooting at Sandy Hook school in 2012, but some analysts put the figure at closer to three million.
The NRA has boasted some high-profile members over the years, including late former President George HW Bush. He resigned from the group in 1995 after Mr LaPierre referred to federal agents as "jack-booted thugs" in the wake of a bombing attack on a government building in Oklahoma City.
Current members include former vice-presidential candidate Sarah Palin, and actors Tom Selleck and Whoopi Goldberg. The late actor Charlton Heston - a former NRA president - famously held a rifle over his head following the Columbine High School mass shooting in 1999, telling gun control advocates they would have to take it "from my cold, dead hands".
Why is it controversial?
The NRA lobbies heavily against all forms of gun control and argues that more guns make the country safer.
It relies on, and staunchly defends, a disputed interpretation of the Second Amendment to the US Constitution, which it argues gives US citizens the rights to bear arms without any government oversight.
The association faced criticism from both sides of the political spectrum in the wake of the Sandy Hook shooting, when Mr LaPierre said that the lack of an armed guard at the school was to blame for the tragedy.
It staunchly opposes most measures that would restrict gun ownership.
It strongly supports legislation that expands gun rights such as "open-carry" laws, which allow gun owners to carry their weapons, unconcealed, in most public places.