Joe Biden appeared to announce his candidacy for the 2020 US election, before immediately correcting himself.
The former vice-president made the slip while addressing 1,000 Democrats at a dinner in his home state of Delaware.
He said his record was the most progressive "of anyone running for the United-" before correcting himself and saying, "anybody who would run".
The audience stood up and chanted "run Joe run", while Mr Biden crossed himself and said, "I didn't mean it!"
Addressing party brokers and leaders in the city of Dover, Mr Biden, 76, said that it was time to restore the country's "backbone", but that they needed a political consensus to move beyond what he called today's "mean", "petty" and "vicious" political landscape.
"I'm told I get criticised by the new left," he said, referring to a group of popular new left-wing Democrats that includes congresswoman Alexandria Ocasio-Cortez. "I have the most progressive record of anybody running for the United- "
He then corrected himself, saying: "Anybody who would run."
As the diners rose to their feet and chanted "run Joe run", he laughed and insisted, "I didn't mean it!"
"Of anybody who would run," he continued. "Because folks, we have to bring this country back together again."
Mr Biden, who was Barack Obama's second-in-command from 2009 to 2017, added that the 2020 election will be the most important vote in a century.
Speculation that Mr Biden would announce his candidacy has reached feverish levels.
If he were to run, he would be entering an increasingly crowded race – with 15 other Democrats have already declared their bids.
Among them are senators Elizabeth Warren, Kamala Harris and Bernie Sanders, who ran against Hillary Clinton in 2016. Former Texas congressman Beto O'Rourke joined the race last week.