US President Joe Biden made an error, stating that he will defeat his opponent Donald Trump in the "upcoming election of 2020 again", on Friday, give rise to his age-related concerns. 

The slip of tongue took place when Biden was addressing the public about the forthcoming elections — set to take place in November this year. 

The 81-year-old on July 4 referred to himself as the "first black woman to serve with a black president".

Biden’s recent gaffes appear to have worsened following his contentious presidential debate against his Republican rival Donald Trump last week. This raised concerns from the Democratic Party about his ability to serve a second term.

Aside from the error, the current president confirmed that he will be continuing as a candidate in the 2024 presidential election.

Additionally, he also mentioned being forced to withdraw from the forthcoming elections.

“Let me say this as clearly as I can: I’m staying in the race,” Biden asserted. “I’ll beat Donald Trump. I will beat him again in 2020. By the way, we’re going to do it again in 2024. Yeah, I learned long ago that when you get knocked down, you get back up.”

Addressing concerns about his age, he said: “You probably also noticed a lot of discussion about my age. I know I look 40. I keep seeing stories about me being too old. Let me say something…I wasn’t too old to create over 15 million new jobs.”

Moreover, according to CNN, some Democrats are shifting support towards Vice President Kamala Harris.