(AFP) - A mass shooting that left 19 schoolchildren dead in the deeply pro-gun state of Texas on Tuesday increased pressure on US politicians to take action over the ubiquity of firearms -- but also brought the grim expectation of little or no change.

It was the eighth mass shooting this year, according to the Everytown gun control group, and came 10 days after another 18-year-old murdered 10 African Americans at a supermarket in New York.

But nearly 10 years after a man slaughtered 20 children and six others in an attack on the Sandy Hook elementary school in Newtown, Connecticut, and four years after 17 were killed at a Florida high school, restrictions on gun purchases and ownership have not significantly changed.

"I had hoped, when I became president, I would not have to do this, again," a distraught President Joe Biden said as he led national mourning, vowing to overcome the US gun lobby and find a way to tighten gun ownership laws.

"Another massacre... an elementary school. Beautiful, innocent, second, third, fourth graders," he said. "I am sick and tired of it. We have to act. And don't tell me we can't have an impact on this carnage."

But guns of all kinds, especially high-powered assault rifles and semi-automatic pistols are cheaper and more widely available than ever across the United States.

And the all-too-familiar arguments over guns, public safety and rights re-opened immediately on the news of Tuesday's mass shooting.

- Gun massacres 'politicized'? -

The debate is set to intensify going into the weekend when Houston, Texas hosts the annual convention of the country's leading pro-gun lobby, the National Rifle Association.

Scheduled to speak at the convention is former president Donald Trump, Texas Governor Greg Abbott, Texas Senator Ted Cruz and other prominent Republicans.

Senator Chris Murphy, who represents Connecticut, made an emotional call on the Senate floor on Tuesday for lawmakers to take action.

"Nowhere else does that happen except here in the United States of America and it is a choice. It is our choice to let it continue," he said.

But Cruz quickly pushed back, saying people will use the shooting to attack the right of people under the US Constitution's 2nd Amendment to own guns.

"When there's a crime of this kind, it almost immediately gets politicized," Cruz said.

Attacking constitutional gun rights "is not effective in stopping these sort of crimes," he added.

- More guns, more shootings -

Yet data shows the grim national cost of gun crime.

Last week, the Centers for Disease Control and Prevention said the number of gun deaths in the United States underwent a "historic" increase in 2020.

And the US racked up 19,350 firearm homicides in 2020, up nearly 35 percent over 2019, and 24,245 gun suicides, up 1.5 percent.

At 6.1 deaths per 100,000 inhabitants in 2020, the firearm homicide rate was the highest in a quarter century.

Mass shootings have also risen, according to Everytown.

"Since 2009, there have been 274 mass shootings in the United States, resulting in 1,536 people shot and killed and 983 people shot and wounded," the group says.

The country is swamped with guns. US firearms makers produced more than 139 million guns for the commercial market over the two decades from 2000, and the country imported another 71 million.

That includes high-powered assault rifles, which can be found for $500, and 9 millimeter pistols that combine ease of use, high accuracy and semi-automatic triggers with prices as low as $200.

- Gun laws eased in Texas -

But at every incident, proposals by state and federal lawmakers to tighten laws are rebuffed by conservative colleagues, who count on voter support from a sizeable portion of the public opposed to gun control.

Last year, a Pew poll said just 53 percent of Americans want stricter gun laws, and only 49 percent think tougher laws would decrease mass shootings.

Politicians like Abbott have instead moved to ease controls. Last year, the Texas governor signed a law allowing anyone in the state over 18 to openly carry a handgun without a license or training.

Shannon Watts, the founder of Moms Demand, an activist arm of Everytown, pointed out that Texas is one of the country's largest gun markets and has a high firearms death rate.

"If more guns and fewer laws made Texas safer, it would be the safest state with declining rates of gun violence," Watts wrote on Twitter.

"But it has high rates of gun suicide and homicide, and is home to four of the 10 deadliest mass shootings."

© Agence France-Presse