The controversial US House of Representatives member, Alexandre Ocasio Cortez, announced her support for presidential candidate Bernie Sanders.
"We now have the best group of Democratic candidates in a generation, and much of that is due to the work that Bernie Sanders has done in his lifetime," said 30-year-old Okacio Cortez at the festival, which gathered about 20,000 people in her Queens constituency.
Earlier, campaigners for Democratic candidate Bernie Sanders announced that "during one of the electoral activities, Sanders felt a soreness in the chest.
The senator later announced that he was ready to continue working after he was discharged from hospital.
Nineteen candidates are competing for the Democratic presidential nomination, 12 of whom participated in a debate on Tuesday, and Sanders is third in the polls, behind Joe Biden and Elizabeth Warren.
Ocasio Cortez joined her fellow congressional Democratic New Guard Ilhan Omar in support of Sanders.
The two young women MPs belong to the so-called "band", a group of four young, ethnically diverse, leftist and bold young women activists who campaign against President Trump's racist policy.Trump had earlier asked them to "return home," although they are all Americans.