President Joe Biden joined United Auto Workers strikers on a picket line on Tuesday as their work stoppage against major carmakers hit day 12, a demonstration of support for organised labour apparently unparalleled in presidential history.

“Stick with it,” he told them, exchanging fist bumps with grinning picketers as he walked along the line. “You deserve the significant raise you need,” Biden said through a bullhorn while wearing a union baseball cap after arriving at a GM parts distribution warehouse west of Detroit.

He encouraged them to continue fighting for better wages despite concerns that a prolonged strike could slow the economy. He said “yes” when asked if UAW members deserved a 40 per cent raise, one of the union's demands. “No deal, no wheels!” workers chanted as Biden arrived. He was joined by UAW president Shawn Fain.