Joe Biden has been accused of lying about his claim that he met with 'every family' who lost a child in the 2012 Sandy Hook massacre.

JT Lewis, whose six-year-old brother Jesse was one of the 26 people killed in the Connecticut mass shooting, eviscerated the 2020 hopeful for making the claim in a new video released earlier this week.

In that clip, Biden promised to do more to bring about gun control and stated: 'What really got to me, really firsthand, was what happened up at Sandy Hook. I think I met with every one of the parents, and/ or the families of those who were lost.'

However, Lewis hit back on Twitter on Wednesday, writing: 'This is a lie. Obama came to Sandy Hook and met with every family. Joe Biden DID NOT. In fact, my family was not allowed on Air Force One because we refused to support Obama/Biden gun control efforts.'

He later followed up by saying: 'Joe Biden just claimed that he came to Sandy Hook after the shooting and met with every family who lost someone. It was actually Obama who did that, NOT Joe Biden. Biden also thought he was VP when Parkland happened.

Lewis then bluntly added: 'Joe Biden is either a liar or he's losing his mind.'

The 19-year-old - who is running as a Republican in the Connecticut State Senate - appeared on Fox and Friends on Friday morning, where he continued to call out Biden for perceived factual inaccuracies.

JT Lewis, whose six-year-old brother Jesse was killed in the Sandy Hook massacre, has refuted Joe Biden's claim that he met with every family who lost a child in the mass shooting

Lewis - who is a Republican running for the Connecticut State Senate - called out Biden in a series of tweets

'Joe Biden wasn't there, and what he talks about in his videos is firsthand experience with families and first responders, and I wanted to clarify that it was actually President Obama who came there in the days after the shooting and met with us and helped us through that really tragic time,' Lewis told the program.

It's the latest alleged factual inaccuracies that Biden has made on the campaign trail.

Biden and his campaign have struggled in the past few weeks to overcome a narrative of the former vice president's own making: his propensity to confuse and misremember details as he talks to voters.

Additionally, he's been battling questions about his ability to take on President Donald Trump after he made his series of gaffes, resulting in a growing narrative around his age and mental capacities which his team has been fighting to counteract.

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

Six-year-old Jesse Lewis was one of the 26 people killed in the Connecticut mass shooting

The former vice president also mixed up the timeline around the Marjory Stoneman Douglas High School in Parkland, Florida in February of 2018. He said he was in office at the time but he had 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.

Back in August, The Washington Post offered a detail report that showed how Biden got numerous details wrong when he talked about awarding a Navy war hero the Silver Star.

Last month, Biden was forced to address his recent spate of gaffes - including his miscounting of that story - in an interview with Stephen Colbert.

Joe Biden was forced to address his spate of gaffes in an interview with Stephen Colbert

In August, Biden had recounted to a crowd in New Hampshire that during his time as vice president he traveled to Kunar Province in Afghanistan, to award a combat medal to a U.S. Navy captain who had rappelled 60 feet down a treacherous cliff to retrieve a fallen comrade's body.

Poised to pin a silver star on the serviceman's uniform, in Biden's version, he stopped when the sailor told him he didn't deserve it.

'He said, 'Sir, I don't want the damn thing!',' he said last Friday. ''Do not pin it on me, Sir! Please, Sir. Do not do that! He died. He died!''

Biden added: 'That is God's truth, my word as a Biden.' It was false.

The key elements of the story were a Navy captain getting the silver star from Biden in Kunar province for an act of bravery involving rappelling.

Biden visited Afghanistan's Kunar province in 2008, when he was still a U.S. senator, and was there when Major General David Rodriguez bestowed a bronze star on an Army enlisted man - Specialist Milez Foltz.

That is the only medal ceremony in Kunar province which comports with his telling.

But then in 2011, Biden went to Wardak province - where he did bestow a bronze star on a reluctant hero.

Biden pinned the Bronze Star Medal for Valor on U.S. Army Staff Sgt. Chad Workman at Forward Operating Base Airborne in eastern Afghanistan, on Jan. 11, 2011

In Afghanistan: Joe Biden (third from right) was in Kunar Province in 2008, not 2011, and saw a medal ceremony - he did not pin on the medal himself. Also present were then senator Chuck Hagel (left) and John Kerry (right) and (second left) Major General David Rodriguez, who gave the bronze star to an enlisted soldier, not a Navy captain

The recipient, Staff Sgt. Chad Workman, apparently did protest that his bravery wasn't worthy of recognition. He had run into a burning vehicle to save a friend's life, only to discover that his body was already 'melting.'

'I tried to get out of going' to the medal presentation, he told the Post.

But Workman did not rappel at all, did not receive the silver star and was not in the Navy, and was enlisted, not an Army captain.

In fact the Pentagon has no record of any Army captain receiving a Silver Star during the period of time covered by Biden's anecdote.

The daring cliffside descent in Biden's campaign story was that of another man, Army Ranger Kyle J. White, according to the Post.

He got his medal at the White House years later – a Medal of Honor – from President Barack Obama.

That means Biden conflated at least three stories which took place over six years and threw in a change of branch and moved the hero from being enlisted to being commissioned.

Challenged on it after the Washington Post published its analysis, he told its columnist Jonathan Capehart: ''I was making the point how courageous these people are, how incredible they are, this generation of warriors, these fallen angels we've lost.

'I don't know what the problem is. What is it that I said wrong?'