Democratic members of the House Committee on Energy and Commerce have written a letter to NFL Commissioner Roger Goodell asking whether the league intends to fulfill a commitment to provide an additional $18 million of funding for research by the National Institutes of Health.

The funding is to be provided as part of a 2012 agreement by the NFL to provide $30 million to support NIH research into brain injuries and other medical conditions affecting athletes through the Sports Health and Research Program. The agreement to establish the research program expires at the end of August unless renewed by the parties.

[A Gray Matter: Two UMaine athletes sidelined by head injuries show what we know — and don’t know — about treating concussions.]

“With little more than a month remaining in the initial five-year agreement establishing SHRP, the NFL has yet to contribute the remaining $18 million pledged to support research into health issues affecting athletes through NIH,” the lawmakers wrote to Goodell. “Since this research is critical to improving our understanding of the increased health risks that athletes face from their sport as well as ways to prevent and mitigate such risks for the future, we would hope that the NFL would follow through on its commitment to provide the balance of its $30 million donation.”

The letter is signed by Rep. Frank Pallone Jr. of New Jersey, the committee’s ranking Democrat, and Gene Green, D-Texas, Diana DeGette, D-Colorado, and Jan Schakowsky, D-Illinois.

The NFL said it intends to honor its commitment.

“We are currently engaged in constructive discussions with the [Foundation for the National Institutes of Health] regarding potential new research projects and the remaining funds of our $30 million commitment,” the league said in a written statement issued through a spokesman.

“In September 2016, the NFL pledged $100 million in support for independent medical research and engineering advancements in neuroscience-related topics. This is in addition to the $100 million that the NFL and its partners are already spending on medical and neuroscience research.”

The letter asks the NFL how and when it plans to distribute the remaining funding. It also asks whether the league intends to renew the commitment and provide additional funding.

A study last year by Democratic members of the committee accused the NFL and its head, neck and spine committee of attempting to influence the research by trying to steer a study to a doctor with ties to the league. The NFL denied the allegations, saying that it raised concerns through appropriate channels.

The $16.3 million of funding that was to be provided by the NFL to that $17.5 million study by Boston University researcher Robert Stern instead was funded by NIH.

Subsequent attempts to put the remaining $18 million in funding to use have been unsuccessful, according to the lawmakers’ letter. According to the letter, NIH rejected an inquiry to use the funding on an ongoing study by a member of the NFL’s head, neck and spine committee, and the NFL did not make a commitment to a research plan proposed by NIH regarding youth concussions.

The letter comes one day after a study by researchers from Boston University and the VA Boston Healthcare System found the degenerative brain disease CTE in 110 of 111 brains studied of former NFL players.