WESTERVILLE, Ohio — Representative Ilhan Omar endorsed Senator Bernie Sanders of Vermont for the Democratic presidential nomination on Tuesday, and Representative Alexandria Ocasio-Cortez will endorse Mr. Sanders at a rally this weekend, according to his campaign.
Ms. Ocasio-Cortez, Democrat of New York and a star of the progressive left, will join Mr. Sanders at his “Bernie’s Back” rally in Queens on Saturday. Earlier Tuesday, his campaign had teased that Mr. Sanders would have a “special guest” at the event.
News of the endorsements came as the Democratic presidential candidates were wrapping up their appearances in the fourth debate of the primary season. Ms. Ocasio-Cortez’s planned endorsement was first reported by The Washington Post.
The endorsements, which come just two weeks after Mr. Sanders suffered a heart attack in Las Vegas, are likely to provide a much-needed boost to Mr. Sanders’s campaign. They could also serve to quell some concerns about his health and his age.
“Bernie is leading a working-class movement to defeat Donald Trump that transcends generation, ethnicity and geography,” Ms. Omar, Democrat of Minnesota, said in a statement.
She cited the bill she and Mr. Sanders introduced in June to cancel all of the country’s student debt, worth about $1.6 trillion, and praised him for working to end foreign wars. “I believe Bernie Sanders is the best candidate to take on Donald Trump in 2020,” she said.
In his own statement, Mr. Sanders called Ms. Omar “a leader of strength and courage.”
Mr. Sanders, 78, has been recovering since his heart attack, first at a hospital and then at his home in Burlington, Vt. The debate on Tuesday night in Westerville, Ohio, just outside of Columbus, was his first appearance before a national audience since the episode.
Mr. Sanders’s health issues have cast a degree of uncertainty over his campaign and left his aides rushing to reassure voters about his age and health, just as he was trying to improve his standing in a race that in recent weeks has become more of a two-person contest between Senator Elizabeth Warren of Massachusetts and former Vice President Joseph R. Biden Jr.
Asked about his health directly at the debate on Tuesday night, Mr. Sanders nodded to the rally and to the “special guest.”
“Let me invite you all to a major rally we’re having in Queens,” he said. “We’re going to have a special guest at that event, and we are going to be mounting a vigorous campaign all over this country.”
He also said, “I’m feeling great.”
Mr. Sanders’s campaign is billing the New York rally as his official return to the campaign trail. It had toyed with holding the rally in Prospect Park in Brooklyn, according to an aide, but settled on a park in Queens, with a backdrop of the Manhattan skyline.
Presidential endorsements from the congresswomen, both members of the group of first-term Democratic women of color known as “the squad,” were highly coveted. In addition to being among the country’s most prominent progressives, they have also become some of President Trump’s favorite foils.
Last month, Ms. Warren won the endorsement of the Working Families Party, a progressive group that endorsed Mr. Sanders during the last presidential cycle.
The endorsement was a boon to Ms. Warren’s candidacy as she aimed to position herself as Mr. Biden’s main rival and the standard-bearer for the progressive left. But it also unnerved supporters of Mr. Sanders, who criticized the endorsement process.
Matt Stevens contributed reporting from New York.