Boston City Hall

At-large City Councilor Michelle Wu landed what could be one of her most consequential endorsements to date as she tries to become Boston’s next mayor.

Congresswoman Ayanna Pressley endorsed Wu over rival and fellow former City Council colleague Annissa Essaibi George early Friday morning. Pressley was the first woman of color to win a spot on the Boston City Council in 2009; Wu was the second in 2012.

Pressley had refrained from endorsing a candidate during the primary.

“I’ve worked closely with Michelle Wu for nearly a decade. Michelle has a passion for service and a vision for our city that is grounded in her own lived experience and belief in the transformative potential of policy. At this pivotal moment in our city’s history, we need bold leadership – that’s why I’m so proud to endorse Michelle’s candidacy for Mayor. I look forward to continuing to work alongside her to tackle the entrenched challenges of racial, social, economic, healthcare, and environmental injustice facing our communities,” Pressley said in a statement released by the Wu campaign.

Wu and Essaibi George are competing to expand their appeal among voters beyond the bases that carried them to victory in the preliminary election last month – Essaibi George in whiter, middle-class neighborhoods like South Boston, West Roxbury and southeast Dorchester; Wu in liberal bastions like Jamaica Plain and Back Bay.

As a consequence, political observers say the city’s large numbers of Black and Latino voters are will be key to any candidate’s victory. Neither got strong backing in Roxbury or Mattapan, home to many Black voters who strongly supported acting Mayor Kim Janey. Janey also endorsed Wu last weekend.