Democratic leadership contender Joe Biden left voters bewildered yesterday as he told them he was running for the Senate and if they didn't like him they should 'vote for the other Biden'.

The former vice president, 77, sparked fresh concerns over his mental capacity as he addressed a crowd in South Carolina and appeared to forget which campaign he was running in.

He said: 'My name's Joe Biden and I'm a Democratic candidate for the United States Senate. Look me over, if you like what you see help out, if not, vote for the other Biden.'

A clip of his latest gaffe was posted on Twitter by activist Shaun King, who wrote: 'This is so sad.'

He added: 'I honestly wish he would've retired & not subjected himself to the rigors of this campaign.'

Donald Trump Jr took a swipe at Biden on Twitter saying: 'As I've been saying when is enough enough with Joe?'

President Trump's eldest son added: 'He's been running for 18 months and doesn't know what he's running for? If his family wasn't making millions off of his public office they should have stepped in a long time ago. This isn't right.'

Joe Biden left voters bewildered yesterday as he told them he was running for the Senate and if they didn't like him they should 'vote for the other Biden.'

This is so sad.



Here @JoeBiden says to the crowd in South Carolina that he is "running for the United States Senate" and that if they don't like him they can "vote for the other Biden."



I honestly wish he would've retired & not subjected himself to the rigors of this campaign. pic.twitter.com/mygFnsrdjC — Shaun King (@shaunking) February 25, 2020

Joe Biden has made a string of gaffes during the democratic leadership campaign

Other twitter users agreed with one saying: 'His cognitive decline has been on display throughout this campaign. It is sad.'

Another said: 'Biden's brain is complete pudding at this point. He's barely coherent half the time.'

It is the latest in a string of gaffes by Biden in the past few months and comes ahead of tonight's Democratic TV debate in Charleston, South Carolina, and four days ahead of the state's primary.

Bernie Sanders remains the favorite and his six rivals are preparing to try to knock him off his front-runner perch in tonight's keenly-anticipated debate.

Last week's debate in Las Vegas was the fiercest yet as candidates took more personal swipes at one another and it smashed a TV ratings record with nearly 20 million viewers, beating the Golden Globes and the Grammys.

The Vegas debate also caused embarrassment for Biden as he was heckled by protesters chanting 'no kids in cages' as they slammed his record on immigration.

Protesters from RAICES Action, a prominent immigrant rights group, interrupted Biden's closing remarks near the end of Wednesday's two-hour televised debate at the Paris Theater and yelled, 'You deported 3 million people!'

Biden has been Sanders' main rival but his gaffes could cost him dear and he has even upset minority voters who are seen as being key to his success.

Last August Biden blundered in Iowa telling a group of Asian and Hispanic voters that 'poor kids are just as bright and just as talented as white kids.'

Quickly realizing his mistake, the former vice president added 'and wealthy kids. Black kids. Asian kids.'

Biden was today meeting privately with leading black newspaper publishers as he tries to shore up African American support ahead of the South Carolina primary on Saturday.

Biden was meeting with about a half dozen leaders of of the National Newspaper Publishers Association which includes about 200 black-owned newspapers around the country, with a combined audience the group estimates at 20 million.

Donald Trump Jr seized on Biden's latest gaffe saying he 'doesn't know what he's running for'

Joe Biden, right, with his late son Beau, who he wrongly said was US Attorney General

Donald Trump slammed Biden's gaffe about his son on Twitter claiming 'enough is 'enough'

The former vice president is depending heavily on black voters as he looks for his first win of the primary season and attempts to blunt Bernie Sanders' momentum after leading voting in Iowa, New Hampshire and Nevada.

Last week Biden mistakenly described his late son Beau Biden as a former United States Attorney General during a town hall event when in fact he was Attorney General of Delaware.

Donald Trump Jr also seized on that blunder and tweeted Saturday: 'In all fairness Biden has no idea what he's saying or where he is most of the time.

'When will someone close to him finally say enough is enough? It's not right anymore.'

Earlier this month he bungled a reference to which states had already voted saying 'it is important that Iowa and Nevada have spoken' when he should have said Iowa and New Hampshire.

While campaigning in Iowa in September, Biden put the 1968 assassinations of Martin Luther King Jr. and Robert F. Kennedy in the 1970s.

He also mixed up the timeline around the Marjory Stoneman Douglas High School in Parkland, Florida in February of 2018, saying said he was in office at the time when he'd already left the White House.

And in the second presidential debate, he told viewers a number but forgot to tell them they were supposed to send a text to it.

In September he was also called out for getting numerous details wrong when awarding a Navy war hero the Silver Star. He got the soldier's rank and military branch wrong, along with the type of medal involved, the location and timeframe of the crucial moment, and the act of bravery that he was rewarding.

Some have suggested his boyhood stutter might be to blame for his tendency to get his words mixed up.

But Biden has said: 'I've always attributed that to being tired and not to the stutter.'

In December Biden made a gaffe during his 'No Malarkey' bus tour through Iowa when he called a Marine Corps veteran 'fat.'

Merle Gorman, 83 , quizzed him about his involvement in Ukraine and accused him of 'selling access to the president' to which Biden called him a 'damn liar' and said: 'That's not true and no one has ever said that. No one has proved that,' Biden said. But look, fat, here's the deal.'

Last August at the Iowa State Fair he mangled a line from his standard campaign speech, saying, 'We choose truth over facts,' when he meant 'we choose truth over fiction.'

He also referred to himself as 'President of the United States' at the event while responding to a question from DailyMail.com about gun control.

President Trump has repeatedly hit the former vice president on his age, calling him 'Sleepy Joe' and saying 'Joe Biden is not playing with a full deck.'

Last week's TV debate (pictured) smashed viewing records and tonight's is also expected to be a ratings hit. The candidates, from left: Michael Bloomberg, Elizabeth Warren, Bernie Sanders, Joe Biden, Pete Buttigieg, and Amy Klobuchar

RAICES advocacy chief Erika Andiola (left) and its communications manager Lucia Allain interrupted Joe Biden's closing remarks at the Democratic debate last week. They are pictured here at the 2019 Glamour Women Of The Year Awards in New York where the group received an award

In his meeting with black newspaper publishers today, Biden was expected to discuss the affordable housing plan he announced Monday. He also may bring up his proposals for health care, which he has been emphasizing this week with heavily black audiences.

His proposals include a public option government insurance plan that would cover Americans who would have been covered by Medicaid expansion under the 2010 health care law but who live in states whose Republican governors refused to expand Medicaid.

South Carolina is among those states, as are several states that vote March 3 on Super Tuesday.

With mounting fear among the Democratic establishment that Bernie Sanders, the self-described democratic socialist, is on the verge of gaining a significant lead in the delegates needed to secure the nomination, several candidates are resorting to a last ditch effort to stop him.

Protesters interrupted former vice president Joe Biden's closing remarks at last week's Democratic TV debate in Las Vegas

Bernie Sanders' (pictured) Democratic rivals are hoping to put a dent in his lead in tonight's TV keenly-anticipated TV debate from Charleston, South Carolina

The day before Tuesday night's debate in Charleston, they previewed their lines of attack in a series of digital or television advertisements.

Pete Buttigieg, the former mayor of South Bend, Indiana, highlighted Sanders' call for a government-financed health care system as an example of his 'polarization.'

Biden accused Sanders of trying to undermine President Barack Obama's 2012 reelection. And former New York Mayor Mike Bloomberg assailed Sanders' record on gun control.

The new wave of infighting came just hours before seven Democrats were set to meet for the party's 10th - and perhaps most consequential - debate of the 2020 primary season.

Biden is looking to make a big impression in a state where he was long viewed as the unquestioned front-runner because of his support from black voters.

Campaigning in South Carolina the day before the debate, Biden predicted he would win 'by plenty' on Saturday

Having finished on top in three consecutive primary contests - including a tie in Iowa - Sanders is eyeing a knockout blow, however.

He has shifted new staff into the state from Nevada in recent days, expanded his South Carolina advertising and added events to his schedule.

Sanders senior adviser Jeff Weaver said there was an 'air of desperation' to the fresh attacks on his candidate.

'You've got candidates, you've got super PACs, all piling on to stop Bernie Sanders,' Weaver said. 'They know he has the momentum in the race.'

Trump was encouraging the chaos from afar. During a trip to India, the Republican president predicted a long and messy primary season ahead for his Democratic rivals.

'It could go to the convention, it really could,' Trump said. 'They are going to take it away from Crazy Bernie, they are not going to let him win.'

He added, 'I actually think he would be tougher than most of the other candidates because he is like me, but I have a much bigger base.'