Activist Ady Barkan on Wednesday asked former Vice President Joe Biden, the only contender for the 2020 Democratic presidential nomination who has not sat down with the dying healthcare activist, to find time to meet and discuss Medicare for All. 

Barkan, who is suffering from ALS, made the request in a video produced by Now This released Wednesday. The activist is going into surgery thursday for a tracheostomy to help him breathe, but said that after after his recovery, he and Biden should sit down. 

"The surgery will be intense, and I'll be in the hospital for a week of recovery," Barkan says in the video, speaking through his standard video screen that allows him to talk via eye movements. "But I'll be out soon and back in the struggle with you."

Despite his illness, Barkan has been at the forefront of the campaign to win Medicare for All, talking on camera with five candidates for president: Sens. Elizabeth Warren (D-Mass.), Bernie Sanders (I-Vt.), Cory Booker (D-N.J.), and Kamala Harris (D-Calif.), as well as former Secretary of Housing and Urban Development Julián Castro. South Bend, Indiana Mayor Pete Buttigieg, former Rep. Beto O'Rourke (D-Texas), Sen. Amy Klobuchar (D-Minn.), and businessman Andrew Yang have all agreed to speak with Barkan. 

Not all the candidates support Medicare for All. Some, like Biden, want to stick with a private system but improve it and are critical of Medicare for All.

But Biden is the only candidate of the top tier to not answer the invitation to speak with the dying activist. 

"Share your personal and powerful story like your colleagues," Barkan said, referring to Biden's oft-repeated story of losing his son Beau to brain cancer, "and explain your vision of healthcare in America." 

Barkan ended his appeal on an emotional note. 

"Look a dying man in the eyes and tell me how we fix this country," said Barkan. "We may disagree, but that's okay."