Last week, 1,500 unionized nurses gathered in a large conference room at the Marriott Marquis in San Francisco to cheer for a cause they’ve championed for years: Medicare for All.

Considered a radical and even fringe idea for decades, interest in sweeping healthcare reform has surged as progressive Democrats have won a series of primary victories ahead of November’s crucial midterm elections. Most prominent among its advocates is Democratic US Senate nominee from Michigan Abdul El-Sayed – who took the lectern before these nurses.

“Medicare for who?” asked El-Sayed – “ALL!” the crowd shouted back.