United Auto Workers Region 9A union (UAW) is throwing its support behind former New York City Council Speaker Melissa Mark-Viverito, the first labor union to support Mark-Viverito in her run for the 15th Congressional District race. The endorsement comes a day before candidates in the crowded race start collecting signatures to get on the June Democratic primary ballot.

“Although we have relationships with several of the candidates in this race, our bond with Melissa is strong,” Beverley Brakeman, UAW Region 9A director, said in a statement. “From her days as a City Councilwoman and then Speaker, Melissa always stood by us, fighting hard not only for the needs of our members, but for every New Yorker. As a constant champion for workers’ rights, Melissa lead the charge against economic inequality and other systemic injustices throughout New York City, never once backing down from fighting for what is right.”

Mark-Viverito, a progressive Democrat who entered the race in August, called the support “an honor,” especially for one who comes from a union family. “When I served as Speaker, I was proud to stand alongside members of UAW Region 9A as we fought for safe and affordable housing, and expansion to workers rights, and for legal representation for families that were facing wrongful evictions,” wrote Mark-Viverito in a statement.

Brakeman added that Mark-Viverito’s consistent support for the island of Puerto Rico–home to a large UAW presence, and which has been ravaged by Hurricane Maria and a recent earthquake–also sealed the deal. Mark-Viverito has made trips to the island throughout its recovery period. “The choice for us was clear. We know that Melissa will bring her passion to Congress and be the champion we all need,” said Brakeman.