A spending bill headed for a vote in Congress will clarify that the Centers for Disease Control and Prevention may research gun violence, altering a statute that has spanned more than two decades.

A handful of Democrats had wanted to repeal the provision on gun violence, known as the Dickey Amendment, because they said it has blocked gun violence research. Instead, an agreement was made to alter the language of the amendment. The bill is expected to be released Wednesday.

The Dickey Amendment prohibits federal agencies from advocating or promoting gun control, but opponents say it has often been misinterpreted as a ban on gun violence research. It has been in place since 1996, and public health experts have said that inadequate research has left a hole in their understanding of how to prevent gun deaths and injuries.

During hearings about the budget, Health and Human Services Secretary Alex Azar said he did not think the Dickey Amendment prohibits the agency from researching gun violence.

"My understanding is that the rider does not in any way impede our ability to conduct our research mission," he said. "We're in the science business and the evidence-generating business, and so I will have our agency certainly working in this field, as they do across the broad spectrum of disease control and prevention."

Recent mass shootings at a country music concert in Las Vegas and at a high school in Parkland, Fla., have brought attention to the law, with several members saying it must be changed.

Rep. Stephanie Murphy, D-Fla., oversaw the effort on the House side and celebrated on Twitter Wednesday when it was announced the omnibus would contain a change to the language.

"It's a victory for our country and children," she wrote. "Our work to stop gun violence will continue."

Congress must pass the spending bill ahead of a Friday deadline to avoid a partial government shutdown.