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.

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

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