Two progressive heavyweights, Alexandria Ocasio-Cortez and Michael Moore, endorsed Democratic presidential candidate Bernie Sanders in New York City on Saturday as he re-emerged on the campaign trail after having a heart attack earlier this month.

"I am more than ready to take on the greed and corruption of the corporate elite and their apologists," Sanders told thousand of supporters in Queens. "I am more ready than ever to help create a government based on the principles of justice, economic justice, racial justice, social justice and environmental justice."

He added, "To put it bluntly, I am back!"

Ocasio-Cortez and Moore took the stage at the Vermont senator's "Bernie's Back" rally in Queens to explain to a crowd of 20,000 why they were "feeling the Bern."

Ocasio-Cortez said Sanders had been fighting for her entire life for the same issues that got her elected to Congress, emphasizing that when she was a child the senator had already been actively supporting public education, equitable housing, single-payer healthcare, LGBTQ rights and reduction of student debt.

"Bernie Sanders did this and fought for these aims and these ends when they came at the highest political cost in America," she said.

She said her experience in Congress standing up "to corporate power and established interests" further pushed her to support Sanders' candidacy.

"I have grown to appreciate the enormous consistent and nonstop advocacy of Sen. Bernie Sanders," she said.

The handful of speakers used their time on stage to attempt to push back against a narrative that Sanders is too old to run for president and could not be elected.

Moore claimed that news pundits were pushing forward this narrative that Sanders’ age and health would be an issue for his campaign. According to the filmmaker, Sanders’ age would only be a benefit.

“Here’s what’s too old: the electoral college is too old,” Moore said. “A $7.25 minimum wage: that’s too old. Women not being paid the same as men: that’s too old. Thousands and thousands of dollars of student debt. What is that? Too old.”

Moore also talked about challenges around the use of fossil fuels and high healthcare costs and said that the country would benefit from Sanders’ “wisdom and experience and love for the American people.”

"Not only can Bernie win, Bernie will win," Moore added.

That idea was also emphasized by Carmen Cruz, the mayor of San Juan, Puerto Rico, who also spoke at the rally. She said Sanders earned her support when he came to the island without cameras and asked how he could help her constituents.

Many of the other speakers — who included the senator's wife, Jane Sanders, and his national campaign co-chair Nina Turner, a former Ohio state senator — also drew attention to these same issues.

But the greatest focus was on Ocasio-Cortez, who told NBC News before her speech that it was not a political calculation but "authenticity" that drove her endorsement.

“It was a moment of clarity for me personally in saying, ‘What role do I want to play?’” the congresswoman said. “And I want to be part of a mass movement.”

Sanders said he would be joined by a special guest at his rally during Tuesday's debate, and it was later revealed that Ocasio-Cortez and Rep. Ilhan Omar — both members of the so-called "squad" of four progressive congresswomen — would be endorsing the Vermont senator.

Ocasio-Cortez's endorsement is seen as a blow to Sen. Elizabeth Warren, who had previously made an effort to work with Ocasio-Cortez on multiple issues, including in helping with Puerto Rico's recovery after Hurricane Maria.

Nevertheless, Ocasio-Cortez's roots go back to Sanders' 2016 campaign for which she volunteered.

Sanders also praised Ocasio-Cortez when she won her seat in a long-shot bid against a powerful Democratic incumbent in a primary last year. "What she did is talk about the real issues," he said then.

Ocasio-Cortez returned the praise on Saturday, saying that Sanders had changed the direction of the party.

"We right now have one of the best Democratic presidential primary fields in a generation," she said, "and much of that is thanks to the work that Bernie Sanders has done in his entire life."