Donald Trump melts down after the International Firefighters Union endorses Joe Biden for president:  “The dues sucking firefighters leadership will always support Democrats.”

Trump tweeted: “The Dues Sucking firefighters leadership will always support Democrats, even though the membership wants me. Some things never change!”

Biden clapped back: “I’m sick of this President badmouthing unions. Labor built the middle class in this country. Minimum wage, overtime pay, the 40-hour week: they exist for all of us because unions fought for those rights. We need a President who honors them and their work.”

The executive board of the International Association of Firefighters met and voted to ratify its endorsement of Biden hours after he launched his presidential campaign. IAAF President Harold Schaitberger made the endorsement official in an online video and on MSNBC’s Morning Joe on Monday.

“Joe’s a lot like our firefighters. He’s a problem solver who cares deeply about America, and [is] committed to making our country better,” Schaitberger says.

“Schaitberger and other firefighters union members will join Biden as he holds his first public campaign event Monday in a city closely associated with then union movement, Pittsburgh,” NBC News reports.