WASHINGTON (AP) — President Joe Biden picked up the endorsement of North America’s Building Trades Unions at a Wednesday event where the president and his allies set out to dismantle Republican Donald Trump’s reputation as a successful real estate developer.

“Donald Trump is incapable of running anything,” said Sean McGarvey, the organization’s president. “God help us if he gets anywhere near the White House in the future.”

The event, held in a Washington hotel ballroom with a boisterous crowd of union members, was another salvo in the battle for votes from blue collar workers. Trump has tried to chip away at Democrats’ traditional advantage with organized labor, while Biden has been adding to his roster of endorsements and trying to fend off his predecessor’s comeback bid.

Biden said unions would help him make Trump a “loser again,” and he mocked Trump’s inability to pass infrastructure legislation when he was president, saying “he never built a damn thing.”