Rep. Alexandria Ocasio-Cortez (D-New York) introduced Democratic candidate Bernie Sanders at his rally Saturday, by officially endorsing his presidential campaign.

His first rally after suffering a heart attack at the beginning of October, drew a crowd of 25,872 people, his campaign told reporters.

Standing in a park next to a public housing complex in Queens, N.Y., the Democratic socialist Ocasio-Cortez praised the progressive agenda Sanders has pushed.

“No one wanted to question the system, and in 2016, he fundamentally changed politics in America,” she told the crowd. “We right now have one of the best Democratic presidential primary fields in a generation and much of that is thanks to the work that Bernie Sanders has done in his entire life.”

Sanders joined her on stage, saying he was “so delighted” to have her support and called her “an inspiration to millions of young people not just here in New York but across this country who now understand the importance of political participation and standing up for justice.”

Ocasio-Cortez had previously struggled in deciding whether to endorse Sanders or Sen. Elizabeth Warren (D-Massachusetts).

SLIDESHOW: TOP DEMOCRATS RUNNING FOR PRESIDENT IN 2020

She told CNN in May that she “would like to see in a presidential candidate is one that has a coherent worldview and logic from which all these policy proposals are coming forward. I think Sen. Sanders has that. I also think Sen. Warren has that.”

Warren’s campaign has skyrocketed her to the top of polls, while Sanders has faltered amid his health setback.

Sanders told his supporters Saturday that he is “more than ready to assume the office of president of the United States.”

“To put it bluntly,” he said, “I am back.”

At the rally, Ocasio-Cortez credited Sanders for being her political inspiration.

“The only reason that I had any hope in launching a long-shot campaign for Congress is because Bernie Sanders proved that you can run a grassroots campaign and win in an America where we almost thought it was impossible,” Ocasio-Cortez said.

She added that Sanders helped her develop socialist values saying, “It wasn’t until I heard of a man by the name of Bernie Sanders that I began to question and assert and recognize my inherent value as a human being that deserves health care, housing, education and a living wage.”

She told CBS News Saturday that endorsing Sanders was not politically motivated, but was rather “the most authentic decision to let people know how I feel and where I am.”