New York, Oct 20 Democratic presidential candidate Bernie Sanders returned to the campaign trail with a massive rally in New York City after a recent heart attack that threw the future of his candidacy into question.

Standing in front of what his campaign said was nearly 26,000 people at the Queensbridge Park in Queens with an estimated 10,000 people were left outside the premises due to permit restrictions, Sanders on Saturday said he was "more than ready" to assume the office of US President following the October 1 heart attack, reports Efe news.

"I am more than ready to take on the greed and corruption of the corporate elite and their apologists," Sanders told his ecstatic supporters who had gathered at the "Bernie's Back" rally, which had the highest attendance of any Democratic primary contender so far. "And I am more ready than ever to create a government based on the principles of justice,"

"To put it bluntly," he added, "I am back."

Sanders and his campaign are hoping for a revival to tick up his sluggish poll numbers - which show a notable lack of support among older voters - following two weeks off the campaign trail that raised questions about the future of his bid. Aides and allies of Sanders said Saturday's massive event was a sign of positive things to come.

He also secured two major endorsements with progressive Democratic social-media stars New York Representative Alexandria Ocasio-Cortez and Minnesota Representative Ilhan Omar. Ocasio-Cortez introduced Sanders on Saturday.

At 78, Sanders is the oldest candidate in the field, but supporters said his age was an asset because it meant wisdom of life experience.

But Sanders has remained stagnant in polls. Fellow progressive Massachusetts Senator Elizabeth Warren has risen, closing the gap with former Vice President Joe Biden, who has long been the front-runner.

A Wall Street Journal/NBC News poll from September, before the Vermont Senator's heart attack, found that he had the support of 27 per cent of Democratic voters under the age 50, but just 3 per cent of voters over 50.

Meanwhile, Warren drew a quarter of voters from each age group. Biden had support from 17 per cent of those surveyed under 50 and 42 per cent of Democratic primary voters over.

Sanders has nearly $34 million on hand, about $8 million ahead of Warren's nearly $26 million. He is $25 million ahead of Biden, who has just about $9 million on hand.

He also has attracted over a million grass-roots donors.

Sanders returns to campaign trail with massive NYC rally