Three other freshman women of color, Reps. Ilhan Omar of Minnesota, Alexandria Ocasio-Cortez of New York and Rashida Tlaib of Michigan, have campaigned with Sanders, a Vermont senator.
But Pressley chose Warren. She said in a video posted Wednesday: "For Elizabeth and for me, power belongs in the hands of the people. That's why she's fighting for fundamental change."
Pressley, Ocasio-Cortez, Omar and Tlaib are outspoken progressives seen as rising stars in Democratic circles. They've also been frequent targets of President Donald Trump.
Warren is now a Democratic primary front-runner along with former Vice President Joe Biden, while Sanders runs third in many polls.
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