Walmart employees react after a gunman opened fire in El Paso. (Mark Lambie/El Paso Times/Associated Press)

Shortly after a gunman opened fire at a Walmart and shopping mall in El Paso, a shaken Beto O’Rourke took the stage at a labor forum in Las Vegas.

The Democratic presidential hopeful and former congressman, who lives in the Texas border city, told the audience that he had just called his wife to make sure she was okay. He said the shooting shatters “any illusion that we have that progress is inevitable” when it comes to tackling gun violence.

“We have to find some reason for optimism and hope or else we consign ourselves to a future where nearly 40,000 people a year will lose their lives to gun violence and I cannot accept that,” O’Rourke told reporters afterward.

Across the country, lawmakers took to cable television and Twitter to react to the mass shooting, with Republicans offering prayers and condemnations of the violence without mentioning guns and Democrats going a step further to decry yet another missed opportunity to address the nation’s gun laws. It was similar to what these lawmakers said less than a week ago, when a 19-year-old opened fire with an assault-style rifle at a food festival in Gilroy, Calif., killing three people and wounding 12 others.

On Saturday, President Trump and Vice President Pence offered expressions of condolence and federal support in the mass shooting that left dozens dead and injured in Texas.

“Terrible shootings in ElPaso, Texas,” the president tweeted as the reports of carnage unfolded. “Reports are very bad, many killed. Working with State and Local authorities, and Law Enforcement. Spoke to Governor to pledge total support of Federal Government. God be with you all!”

Texas lawmakers tweeted condolences. Attorney General William P. Barr issued a statement calling for the killer or killers to be “held accountable swiftly and to the fullest extent the law allows.”

“My heart is with everyone in El Paso struck by this unspeakable evil,” Sen. Ted Cruz (R-Tex.) tweeted Saturday afternoon. “Heidi and I are praying for the victims and their families and grateful for the first responders, local authorities, and law enforcement officers working tirelessly to bring the perpetrator of this depraved act to justice and keep the entire community safe. There are millions of people in Texas and across the country standing behind you.”

But Trump and Pence stopped short of calling for action on gun violence. That was left to Democrats, who called on their GOP colleagues to tighten gun laws.

“Enough is enough,” House Speaker Nancy Pelosi (D-Calif.) said in a news release, echoing a phrase that reverberated on social media all afternoon. “The Republican Senate’s continued inaction dishonors our solemn duty to protect innocent men, women and children and end this epidemic once and for all.”

For Democrats, the shooting has the potential to raise the profile of gun control.

The Democratic contenders for president are largely in agreement on the need for greater gun restrictions. Sens. Kamala D. Harris (Calif.) and Cory Booker (N.J.) have offered robust plans. Rep. Eric Swalwell (Calif.), who dropped out of the race in July, had made gun control the centerpiece of his campaign.

“I think all over the world people are looking at the United States and wondering: What is going on?” Sen. Bernie Sanders (I-Vt.) said at Saturday’s forum by the American Federation of State, County and Municipal Employees (AFSCME). “It’s not just today. It has happened several times this week. It has happened here in Las Vegas.”

Sen. Amy Klobuchar (Minn.) told the crowd that her mind was on El Paso — and pledged to take on the National Rifle Association. “I’m someone that believes that we need to take on the NRA.”

She noted that the House of Representatives passed legislation to expand background checks for people seeking to purchase guns. “Do you know where that bill is right now? It’s sitting on [Senate Majority Leader] Mitch McConnell’s doorstep in the graveyard in the Senate.”

McConnell (R-Ky.) tweeted Saturday: “The entire nation is horrified by today’s senseless violence in El Paso. Elaine’s and my prayers go out to the victims of this terrible violence, their families and friends, and the brave first responders who charged into harm’s way.”

The Democratic presidential candidates are embracing gun control more than in any other campaign in recent memory, with emotional appeals against firearms violence and pledges to stand up to the NRA. In the face of more and more mass shootings, particularly in schools, the ground on the issue has shifted from an embrace of a gun culture in many areas of the country, including some that Democrats hope to wrest from the president.

Almost every candidate in the field supports universal background checks and bringing back a ban on the sale of “assault” weapons like the one that expired in 2004.

South Bend, Ind., Mayor Pete Buttigieg said he had an opening statement prepared for his AFSCME appearance, but began his remarks by saying, “I can’t even think about it right now.”

“We can respect the Second Amendment and not allow it to be a death sentence for thousands of Americans,” he added.