Joe Biden's White House bid has been rocked by a series of verbal slip-ups days before South Carolina's Democratic primary, a make-or-break contest as the former vice president struggles to reverse his campaign's slide.
Eclipsed by a surging Bernie Sanders, Biden suggested to supporters Monday that he was campaigning "for the United States Senate" -- where he served for 36 years, until a decade ago.
Biden also blundered by saying he had negotiated the 2015 Paris climate accord with China's Deng Xiaoping, who died in 1997.
Biden, 77, is known for his verbal stumbles. While they may not be disqualifying -- last year he mixed up then-prime minister Theresa May with Margaret Thatcher -- they are providing ammunition for critics who question his mental acuity.
The latest gaffes come as Biden seeks to make a "comeback" after miserable showings in Iowa and New Hampshire and a second-place finish in Nevada, and days before Saturday's primary, a monumental test for his campaign.
Speaking at a Democratic Party Dinner in Charleston, South Carolina, Biden asked the attendees, many of them African Americans who support his bid, for help in making him the nominee.
"Where I come from you don't get far unless you ask," Biden said. "I'm a Democratic candidate for the United States Senate. Look me over. If you like what you see, help me out."
Several US media reported that he added "if not, you can vote for the other Biden," although review of the video does not conclusively show him saying his name. No other Bidens are in the race.
There was no mistaking Biden's error at a second event, when he claimed to have worked on the Paris climate accord with a Chinese leader who died 19 years before the deal was signed.
"I'm the guy that came back after meeting with Deng Xiaoping and making the case that I believe China would join if we put pressure on them," Biden said.
The error was quickly pointed out by President Donald Trump's re-election campaign.
"I honestly wish he would've retired & not subjected himself to the rigors of this campaign," added online personality, activist and Sanders surrogate Shaun King.
Biden was to take the debate stage Tuesday with six rivals: Sanders, former mayors Michael Bloomberg of New York and Pete Buttigieg of South Bend, Indiana, senators Elizabeth Warren and Amy Klobuchar, and billionaire activist Tom Steyer.