Amid growing calls for him to step down due to concerns over his mental and cognitive acuity, President Joe Biden committed a series of notable gaffes during the NATO summit on Thursday.

In a series of embarrassing blunders, Mr confused Vice-President Kamala Harris for Donald Trump and mistakenly referred to Ukrainian President Volodymyr Zelensky as Russian President Vladimir Putin.

The 81-year-old president, who has faced increasing scrutiny from his party regarding his suitability for a second term, ignited yet another controversy as he struggled with basic details at the international summit.

When asked about Ms Harris’ potential to defeat Mr Trump in the 2024 election, Mr Biden said, “Look, I wouldn’t have picked Vice-President Trump (sic) to be vice-president, did I think she’s not qualified to be president.”

He added, “So let’s start there, number one. The fact is that the consideration is that I think I’m the most qualified person to run for president. I beat him once, and I will beat him again.”

Again, Mr Biden erred when introducing the President of Ukraine during the summit, mistaking him for Vladimir Putin of Russia.

“And now I want to hand it over to the president of Ukraine, who has as much courage as he has determination. Ladies and gentlemen, President Putin. President Putin,” Mr Biden said before realising his mistake and correcting himself.

Mr Biden’s errors further amplify existing doubts about his cognitive decline. In a post on Truth Social, Donald Trump took the opportunity to mock the American president.

“Crooked Joe begins his ‘Big Boy’ press conference with, ‘I wouldn’t have picked Vice President Trump to be vice president, though I think she was not qualified to be president.’ Great job, Joe!” Mr Trump wrote.