In a video posted on the Markey campaign’s YouTube account Friday , Ocasio-Cortez calls Markey “a proud and strong progressive champion for working families. Not just in Massachusetts, but across the country.”

Ocasio-Cortez and Markey have worked together as the primary sponsors of the Green New Deal, the signature legislative issue for both lawmakers.

Representative Alexandria Ocasio-Cortez, the young liberal icon from New York, has endorsed Senator Ed Markey’s reelection bid next year, as Representative Joe Kennedy III considers challenging Markey for what promises to be the nation’s most competitive congressional primary.

“Ed Markey, I know, is one of the strongest progressives that we have in the United States Senate,” Ocasio-Cortez said. “And in a time right now, when we have to have conversations not just about holding this administration accountable but changing the Democratic Party for the future, Ed Markey has a very critical role in making sure that climate change, as well as a bevy of other issues — health care and beyond — are critical core issues in how we fight for working people and working families in the United States.”

The endorsement from Ocasio-Cortez may serve to undercut one of the biggest premises of a Kennedy challenge to Markey: the call for a generational change from Markey, 73, to Kennedy, 38. At 29, Ocasio-Cortez last year became the youngest woman ever to be elected to Congress.


“In the fight to save our planet and unleash a clean energy future, I am proud to partner with Alexandria Ocasio-Cortez and honored to have her endorsement for re-election,” Markey said in a statement. “I am so fortunate to call Alexandria my friend and colleague, and I am proud to have her support.”

Kennedy opened a Senate exploratory committee earlier this month, but has not publicly decided whether he will jump into the contest. A Boston Globe and Suffolk University poll released last weekend found Kennedy leading Markey by 14 points in a hypothetical match-up. Kennedy led among voters in every sub-group, including younger and older voters.


Asked about the Ocasio-Cortez endorsement, a Kennedy spokeswoman said the four-term congressman is “grateful for the feedback he has received so far from the people of Massachusetts, who are — and will remain — the focus of any campaign he runs.”

Since news of Kennedy’s potential Senate run became public last month, Markey has been securing his support in Washington, a move to ensure that he has a well-financed campaign. So far, he and Kennedy have approximately $4 million apiece in their campaign coffers.

Earlier this week, Markey got the backing of the Democratic Senatorial Campaign Committee, the official organization tasked with electing a Democratic majority to the Senate.

In addition, Senator Joe Manchin, a moderate Democrat from West Virginia, backed Markey earlier in the week. And New Hampshire Senator Jeanne Shaheen told Politico, “That kind of intraparty fighting is not good in the long term. And I don’t think it will be good for Joe Kennedy.”

What’s unclear is whether the Ocasio-Cortez endorsement will influence the thinking of Representative Ayanna Pressley of Boston, whose own endorsement will be closely watched in this contest. On one hand, Pressley is close to Ocasio-Cortez as a fellow member of the four-person “squad” of freshman women of color in the House. On the other hand, Pressley’s challenge of entrenched incumbent Mike Capuano was also rejected by the political establishment, but she won — possibly paving the way for Kennedy’s challenge of Markey.


The high-profile Ocasio-Cortez endorsement comes the day before Markey and Kennedy are set to appear at the state Democratic Party’s annual convention in Springfield.

Markey will deliver a keynote speech about the Green New Deal. Kennedy will moderate an afternoon panel about confronting racism in politics.

The other two formally declared candidates in the Democratic race — labor attorney Shannon Liss-Riordan and businessman and author Steve Pemberton — are slated to address party activists as well.

Watch: Alexandria Ocasio-Cortez endorses Ed Markey

James Pindell can be reached at james.pindell@globe.com. Follow him on Twitter @jamespindell. Click here to subscribe to his Ground Game newsletter on politics.