U.S. Representative Alexandria Ocasio-Cortez, one of the leaders of the party's progressives and a frequent target of Trump attacks, joined the "Bernie's Back" rally in Queensbridge Park and formally endorsed Sanders for the White House. 

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Squad's Ilhan Omar, AOC Endorse Bernie Sanders for President

The rally was Sanders' first event on the campaign trail since Oct. 1 when he had cardiovascular issues. The U.S. senator had returned to his home in Burlington, Vermont, to recover.

But Sanders was back to participate in Tuesday night's three-hour Democratic debate, and he has will resume a full-tilt campaign pushing signature progressive issues such as a government-run healthcare program and a tax on the wealthiest in the U.S.

The backing of Ocasio-Cortez, who represents a New York district near where Sanders held the rally, is expected to boost Sanders in his efforts for the Democratic nomination.

U.S. Representative Ilhan Omar of Minnesota, another member of a group of progressive first-term congresswomen known as "The Squad," announced her endorsement of Sanders on Tuesday.

A third member of the group, Rep. Rashida Tlaib, is also expected to endorse Sanders, and his campaign said Sanders would tour her Detroit district with her on Oct. 27.