The Amazon Labor Union will affiliate with the International Brotherhood of Teamsters, giving the upstart union the backing of one of the most powerful forces in labor, Teamsters announced Tuesday.

Teamsters said the affiliation decision was approved unanimously by the union’s board on Tuesday, though details of the merger were not immediately made clear. The union represents about 1.3 million workers in the U.S. and Canada.

“Today is an historical day for labor in America as we now combine forces with one of the most powerful unions to take on Amazon together,” ALU President Christian Smalls said on social media platform X. “Our message is clear we want a Contract, and we want it Now. We’re putting Amazon on notice that we are coming!”

ALU formed in 2022 as a grassroots organization representing the workers of Amazon’s JFK8 warehouse facility in New York City. Workers became the first Amazon warehouse employees nationwide to be represented by a union.