Ady Barkan has lost his ability to speak, but he has not lost his voice.

On Tuesday, the 35-year-old lawyer and activist, who is dying of amyotrophic lateral sclerosis, or ALS, testified at a “historic” Capitol Hill hearing on Medicare for All.

Addressing the House rules committee through a computer system that tracks his eye movements and then converts text into speech, Barkan offered his own experience with a terminal illness as a case study for why Congress should dramatically overhaul the nation’s healthcare system.

“Every month since my diagnosis, my motor neurons have died out, my muscles have disintegrated, and I have become increasingly paralyzed,” he said. “I am speaking to you through this computer because my diaphragm and tongue are simply not up to the task. Although my story is tragic, it is not unique.”

Barkan told lawmakers that his family had “comparatively good private health insurance” but still pays about $9,000 a month for around-the-clock home care. The alternative, he said, would be to go on Medicare and move into a nursing home, which would take him away from his wife and son.

“We are cobbling together the money, from friends and family and supporters all over the country. But this is an absurd way to run a healthcare system,” he said. “GoFundMe is a terrible substitute for smart congressional action.”

He continued: “Like so many others, Rachael and I have had to fight with our insurer, which has issued outrageous denials instead of covering the benefits we’ve paid for. We have so little time left together, and yet our system forces us to waste it dealing with bills and bureaucracy.”

Barkan was recognized by the committee’s chairman, Jim McGovern – a Democrat from Massachusetts and a co-sponsor of Medicare for All – as “a father, a husband, and, out of circumstance, a healthcare activist”.

“No one should have to fight a healthcare company when they’re fighting for their lives,” McGovern said.

Barkan was added to the witness panel last week as progressives voiced concern that the hearing lacked a strong proponent of the healthcare proposal.

The event was a significant achievement for healthcare activists and a marker of how popular Medicare for All has become on the left. Public support for a single-payer healthcare system has jumped since 2016, when Bernie Sanders made the proposal a centerpiece of his presidential run. And this time around, Sanders is far from the only 2020 presidential contender to embrace the idea.

Representative Ilhan Omar speaks with Barkan. Photograph: J Scott Applewhite/AP

The committee considered the Medicare for All Act of 2019, a House bill introduced earlier this year by the congresswoman Pramila Jayapal that would transition the US to a government-run healthcare system that covers every American. Sanders has introduced a similar proposal in the Senate.

Over the course of several hours on Tuesday, lawmakers and witnesses held a relatively substantive discussion on Medicare for All, including how much the plan would cost, what healthcare providers would be paid, how to transition to such a system and what benefits it could feasibly cover.

McGovern opened the hearing by saying he believed healthcare should be “a right for all, not a privilege for the lucky few”.

The committee’s ranking member, Tom Cole, a Republican of Oklahoma, said the “socialist proposal” would increase taxes, lengthen the waiting periods for care and lower the quality of healthcare Americans received.

Medicare for All “would completely change America’s healthcare system and not, in my view, for the better”, he said.

Throughout the discussion, Barkan’s presence was a visceral reminder of the real-world implications of healthcare policy – and members of both parties recognized his sacrifice.

The House speaker, Nancy Pelosi, who was closely involved in planning the hearing, escorted him to the event. His father, uncle and cousin, as well as a lifelong friend and caretaker, sat nearby. Some activists and onlookers wiped tears from their eyes during his opening remarks.

During a mid-afternoon break for lunch, the congressman John Lewis, a leader of the civil rights movement, came to thank Barkan for his activism. After an emotional exchange, Lewis placed his hand over his heart and said goodbye.

Barkan was diagnosed with ALS in 2016, at 32 years old. He was little known outside of progressive circles until he cornered the former Arizona senator Jeff Flake on a flight from Phoenix to Washington and urged the senator not to vote for the Republicans’ tax plan. Barkan told Flake about his medical condition and said the tax bill threatened crippling cuts to the federal disability program he relied on for coverage.

“Why not take a stand now? You can be an American hero. You really can!” Barkan pleaded. “You could save my life.”

Flake ultimately voted for the measure, but the exchange elevated Barkan’s profile. His group, the Center for Popular Democracy, set up the “Be a Hero” campaign to rally Democrats before the midterms. A profile in Politico called Barkan the “most powerful activist in America”.

In the past two years, he has been arrested multiple times at protests on Capitol Hill, including at one during Brett Kavanaugh’s supreme court confirmation fight.

The cross-country trip from California to the capital was long and arduous. He chronicled parts of the journey on Twitter, noting wryly: “It’s hard with ALS, I won’t lie. Even in this massive wheelchair they still check me at security!”

Before testifying in Congress, he returned to the streets for what his friends fear might be his last DC protest. He joined nearly 200 Medicare for All activists at a rally outside at the headquarters of PhRMA, the Pharmaceutical Research and Manufacturers of America trade association. They held printed copies of crowdfunding websites set up to help pay healthcare costs – a phenomenon the activists blamed on the “greed” of insurance and pharmaceutical companies.

In a brief interview with the Guardian on Monday, Barkan said the hearing was “an incredible opportunity” to make the case for Medicare for All and “show that this is a struggle worth joining and worth sacrificing for”.

“I am hopeful about this country’s future because right now, there is a mass movement of people from all over this country, rising up,” he said. “Nurses, doctors, patients, caregivers, family members – we are all insisting that there is a better way to structure our society, a better way to care for one another, a better way to use our precious time together. If we do the work, we will build the better world our families deserve.”

• This article was amended on 2 May 2019. An earlier version misnamed Ady Barkan as Ady Bryant in the subheading.