A bump stock is attached to a semiautomatic rifle at the Gun Vault store and shooting range in South Jordan, Utah. (Rick Bowmer/AP)

This post has been updated.

Accompanying the $1.3 trillion spending bill that the House passed Thursday afternoon is language that may open the door slightly to restoring federal funding for gun research.

The language, which is still pending passage in the Senate, clarifies that the Centers for Disease Control and Prevention can indeed conduct research into gun violence. For more than two decades, a 1996 rule that Congress passed under pressure from gun lobbyists — known as the Dickey Amendment — has essentially killed federal funding for such research.

In the wake of recent mass shootings in schools, churches and concerts, however, lawmakers have come under renewed pressure to act on gun-related legislation.

The Dickey Amendment states that no CDC funds “may be used to advocate or promote gun control,” banning the public health agency from lobbying for gun control though not explicitly prohibiting gun research. But the rule has had a dramatic chilling effect at CDC as well as throughout other federal agencies, resulting in a near blackout of funding and new data about gun violence.

Gun researchers, gun rights advocates and public health experts were largely dismissive Thursday of how significant the clarification might be. The language is included in a report, attached to the spending bill, that is intended as guidance to federal agencies. The new wording makes lawmakers' intent clear that the text of the Dickey Amendment does not prevent research into gun violence. Even so, the report does not mean that Congress will suddenly divert funds to gun research that it has refused to give for years.

The omnibus bill also includes a provision to improve the National Instant Criminal Background Check System for gun buyers, action that has broad bipartisan support. It marks the only substantive change to gun laws that congressional Republican leaders have brought to vote since the Feb. 14 shooting at Marjory Stoneman Douglas High School in Parkland, Fla., when 17 students and staff were killed.

Together, some Democrats said, the two efforts mark a move in the right direction — but a modest one.

“I welcome them, but I think they were baby steps,” said Rep. Gerald E. Connolly (D-Va.). “How many more massacres of children do we need in the country before we kind of bite into the apple in a serious way?”

Connolly said he is not anticipating the Republican-controlled Congress will be willing to pass any more gun control laws before the election. “I believe if we want serious action by Congress, it’s going to be in the 116th Congress, not this one,” he said.

Some researchers also believe the wording change around funding signals a small shift and an opening, especially among Republican lawmakers who have staunchly opposed any funding for gun-related research.

“It’s recognition by Congress after all these years that, 'Yes, we want to know what the science has to tell us,’ ” said Mark Rosenberg, who directed research on firearm violence at the CDC in 1997 and saw his staff and research projects slashed almost immediately. “It recognizes that science has a tremendous amount to contribute, and that science can be a common ground where both sides come together.”

Others are much more skeptical.

“It means they’ve done nothing,” said David Hemenway, director of the Harvard Injury Control Research Center. “The Dickey Amendment has always been a symbolic gesture to scare away research. This doesn’t change that one bit.”

Garen Wintemute, a leading gun-violence researcher at University of California at Davis, feels much the same. “There’s no agreement on funding. There’s no funding. There isn’t even encouragement,” he said.

The National Rifle Association says nothing would be different.

“The Dickey Amendment is unchanged. It’s what it always has been,” spokeswoman Jennifer Baker said. “It’s only clarifying maybe for people who can’t read because it’s already been written in the original language.”

In a signal of how tepid lawmakers were, Baker pointed out that the new wording doesn’t even cast Congress as the one doing the clarifying. Instead, it quotes Health and Human Services Secretary Alex Azar's recent testimony that “the CDC has the authority to conduct research on the causes of gun violence.”

The race to pass the omnibus came just before the March for Our Lives, a rally against gun violence that could draw as many as 500,000 protesters to Washington this weekend.

House Minority Leader Nancy Pelosi (D-Calif.) said Thursday that she thinks congressional GOP leaders were “rushing” the omnibus bill ahead because “they wanted to get out of town before the march.” And Senate Minority Leader Charles E. Schumer (D-N.Y.) predicted the march would “galvanize action” in the House and Senate. He challenged leaders to put a bill expanding background checks to a vote.

In a speech on the Senate floor on Thursday, Majority Leader Mitch McConnell (R-Ky.) cast the gun provisions as a positive step.

“Thanks to the dogged efforts of Senator Cornyn, the ‘Fix NICS’ provision to repair and improve firearm background checks is also included,” he said. “Both of these bipartisan accomplishments are the direct result of tireless work by those who have been most tragically affected by violence in America’s schools.”

Sen. Marco Rubio (R-Fla.), who embraced new positions on guns in the wake of the Parkland shooting, would not commit to participating in Saturday's march or observing it in any way.

“I don’t know where I’m going to be on Saturday,” Rubio said. He added: “I’m a legislator. I pass public policy. Instead of marching, I should be acting.”

Following the tragedy in Parkland, Rubio had said he would consider embracing limits on the capacity of ammunition magazines and endorsed raising the age requirement for buying a rifle. So far, he has not offered specific policy proposals on either front.

Read more:

What happens to children who survive school shootings in America? 

How the NRA has shaped the world's gun laws?

Health 202: Gun violence research by the government hasn't been funded in two decades. But that may soon change.