Joe Biden grew animated in the congressional conference room in 2016 as, for the first time, he publicly connected the brain cancer that had killed Beau Biden to the toxic burn pits his son had been exposed to during his service in the military.

To Biden, that meant losing his 46-year-old son might not be just an inexplicable tragedy. It also, as Biden soon began making clear, meant his son may have given his life for his country, on account of the time he’d spent on bases in Kosovo and Iraq exposed to airborne toxins.

On the wooden table in front of him, Biden banged on a book — “The Burn Pits: The Poisoning of America’s Soldiers” — whose fourth chapter was titled “Major Biden.” Saying he’d been “stunned” to read the account of Beau’s exposure, Biden told a roundtable on cancer and the firefighters of 9/11, “Guys, I’m going to be the biggest pain in your neck as long as I live, until we figure out about these burn pits.”

But now that Biden is president, many advocates for veterans say he is not going nearly as far or as fast as he should to ensure that soldiers who served near burn pits and other toxic sites receive the health care they deserve.

While Biden often invokes his son Beau to empathize with grieving families or connect with people whose loved ones are deployed overseas, as president he rarely cites Beau’s experience in urging for more help for veterans suffering from their proximity to burn pits.

That mystifies many activists. Veterans groups are becoming more vocal on the issue, and television host Jon Stewart — who championed aid to the firefighters who cleared rubble after the Sept. 11, 2001, terrorist attacks — has also taken up the cause, lobbying Congress and the White House.

Administration officials insist Biden is doing all he can to get help for those who need it.

“Believe me, I feel the urgency. I feel the urgency intensely,” Denis McDonough, Biden’s secretary of veterans affairs, said in an interview. “I feel it in a lot of ways from veterans themselves, and I feel it directly from the president, because the president underscored the urgency of this from Day 1.”

Experts are often uncertain of the link between specific maladies and the burn pits of Afghanistan and Iraq, where the military generated enormous amounts of waste — plastics, batteries, vehicle parts — and then burned it, releasing plumes of dangerous chemicals. Veterans groups have been pressing for years to designate certain ailments as presumptively linked to those pits, automatically triggering federal benefits.

Last Veterans Day, the White House announced measures aimed at addressing the issue, such as exploring whether rules should be rewritten to boost the presumption of a link between burn pits and certain conditions. But in interviews with leaders from seven veterans groups, there was broad agreement that those actions fell far short of what is needed as service members continue to die of toxic exposures.

And some blame Biden, saying they are baffled that he is not pushing harder for a sweeping law to address the issue. “I don’t know why he’s stalling,” said Rosie Torres, who founded the group Burn Pits 360 after her husband returned from Iraq with a debilitating lung disease. “He should be standing in solidarity with the families. Period.”

Torres characterizes VA’s actions as “bureaucratic solutions.” What is needed, she and other advocates say, is comprehensive legislation to automatically cover nearly two dozen medical conditions.

On a recent call with Sen. Jon Tester (D-Mont.), who has filed such a bill, Biden emphasized support but was clear that he wants VA to rewrite its rules as well, according to a White House official, who said administrative actions can take place quicker than any legislative one.

Biden has also emphasized that the actions are for military families, not himself. “The president feels really strongly about this, but I want to disaggregate that from Beau,” McDonough said. “The president feels really strongly about this, because . . . he cares deeply about what our men and women were exposed to over there. Full stop.”

Such comments highlight what some allies believe is the reason Biden has not pressed harder: He does not want to appear to be setting policy based on his personal emotions or grief over his son.

The burden of proof is on veterans to show a direct connection between a disease and their military service. That can be a tough hurdle, particularly for conditions that develop years after a deployment. Studies show that VA rejects the vast majority of claims.

The debate is similar to the one undertaken by Vietnam veterans when, after decades of being denied coverage for exposure to Agent Orange, the landmark Agent Orange Act of 1991 designated a range of conditions as related to military service.

Biden himself drew that parallel during his presidential campaign.

“We’re going to make sure that no veteran is locked out of treatment for conditions related to toxic exposures from burn pits or elsewhere, or traumatic brain injuries they experienced in the line of duty,” he said during a roundtable with veterans in Florida in September 2020. “We made that mistake with Agent Orange.”

In August, VA announced it was granting presumptive status to three additional conditions — asthma, rhinitis and sinusitis. Some 4,000 veterans have received benefits from those conditions, according to McDonough — but advocates say it’s barely made a dent.

“Burn pits claims continue to be denied at an 80 percent rate — these are our concerns, not a runny nose,” said Anthony Hardie, director of Veterans for Common Sense. “There’s a lot of veterans sick, a lot dying, a lot of families suffering. There needs to be substantive change where it matters.”

Over the next 90 days, VA is studying whether to add respiratory and lung cancers to its list of presumptive conditions, and officials also plan to review constrictive bronchiolitis. Not on the list at the moment is glioblastoma, the cancer that killed Beau Biden.

“There’s a lot of work that’s being done on brain cancer, so we’re looking at that,” McDonough said. “I don’t have an announcement on brain cancers right now, but our scientists are cranking on that, too.”

Some activists credit the administration with at least expressing a willingness to address the problem. But Bart Stichman, co-founder of National Veterans Legal Services Program, called it “baby steps, unfortunately.”

Others said Biden’s bureaucratic approach makes little sense, since the science has been understood for decades. “It’s been something we’ve been frustrated with,” said Jeremy Butler, CEO of Iraq and Afghanistan Veterans of America. “Candidate Biden seemed to speak pretty openly about his belief of a connection between Beau’s cancer and the burn pits he was exposed to … The hope was that President Biden would move more rapidly.”

He added, “To continue down the path of doing the traditional way is kind of a slap in the face to the veterans who are literally dying.”

The issue may never have come to Biden’s attention were it not for Joseph Hickman, author of “The Burn Pits.” As Hickman was doing his research, he discovered Beau Biden died of a brain cancer that other service members had also gotten.

Hickman said in an interview he could not conclusively prove that the burn pits caused Beau’s death. “I tried to put two and two together,” Hickman said. “I got a lot of circumstantial evidence pointing that way, but no smoking gun.”

Still, he said he was struck by the abrupt deterioration in Beau’s physical condition. “The guy went to the military, was in perfect physical condition. He had a physical before he left, running miles a day, just in excellent health,” Hickman said. “And then, a short time after he gets back from his deployment, he’s very ill.”

Several others who were serving alongside Beau have also reported being affected by burn pit exposures, and at least three were diagnosed with brain cancer, according to a registry maintained by Burn Pits 360.

One was David McCracken, who like Beau served at Camp Victory in Iraq in 2008. He also went in healthy and strong, but shortly after returning was diagnosed with aggressive glioblastoma. Within a few years, both died at 46.

Like the president, it took McCracken’s wife, Tammy, a few years to draw the connection between her husband’s service in Iraq and his catastrophically deteriorating health.

“When Dave died, I didn’t think it was military-related, I just was sad,” McCracken said. “My grief was normal, like ‘This is what happens when you lose a spouse.’ But when I found out these toxins were responsible, I got really angry. The grief just took a turn.”

For years, she said, VA denied the benefits that accompany a service-related death, and her husband did not receive the burial he had expected in Arlington National Cemetery. McCracken wants Biden to speak out on more: “He’s a parent who’s lost a child. That’s fundamentally connecting us. There’s the hope. I hope he does more. I hope he continues to use the platform he’s got.”

Shortly after Beau died in May 2015, Hickman said he reached out to Biden and to Beau’s widow, Hallie, but didn’t hear back. He sent them copies of his book, but he only learned that it had resonated when Biden began speaking about it publicly.

Biden has at times seemed to be publicly working through the question of what killed his son.

In a January 2018 interview with PBS’s Judy Woodruff, Biden said he thought burn pits played a “significant role.” Still, he said, the science was unsettled.

“There’s a lot higher incidence of cancer coming from Iraq now and Afghanistan than in other wars,” Biden said. “There’s been no direct scientific evidence that I’m aware of yet, but a lot of work is being done.”

During the presidential campaign, he at times tied his son’s military service to his death.

“He spent a year in Iraq and came back decorated, conspicuous service medal honor, bronze star in war zone, etcetera,” Biden, holding back tears during an event in October 2019. “And because of exposure to burn pits — in my view, I can’t prove it yet — he came back with Stage 4 glioblastoma.”

He later urged a law allowing veterans to get treatment, and in the October 2020 issue of Veterans of Foreign Wars Magazine, Biden said he would spend $300 million more on research into the impact of brain injuries and toxic exposures. His budget proposal this year included $87 million toward such research, with additional funding expected in future years, according to McDonough.

“I do believe we are moving quickly and we are looking to find out how we can fine-tune and refine our approaches so we can address these concerns as quickly as possible,” said Terri Tanielian, special assistant to the president for veterans affairs.

John Feal, an activist who has worked with Jon Stewart, was with Biden that day in the Senate conference room. He said the television host met with White House officials recently to urge quicker action on burn pits.

“What is their reason for being so hesitant and not spearheading this and taking this on?” Feal said. “Maybe he doesn’t want his son’s death to be political. But he himself has mentioned this in speeches. I don’t get it.”

Feal said he is frustrated with lawmakers who raise concerns about the cost of covering more veterans when they paid little heed to the cost of the wars themselves.

“Last time I checked they have marble . . . hallways. Don’t say you don’t have the money,” Feal said of the U.S. Capitol. “They say ‘I can’t afford it.’ Dude, I just walked by a statue worth more than my entire house. They went to a war for 20 years and there was no pay-for. Now people are dying, and they say there’s no pay-for.”

And he recalled hearing Biden talk about his son and the need to improve veterans’ care.

“He was passionate about it. I heard it in his voice. He wanted to make a difference,” Feal said. “And then — boom, it fizzles. We’re not going to let this fizzle.”