Barack Obama has expressed private concerns about Joe Biden’s reelection chances, according to CNN. 

Mr Obama and Nancy Pelosi, one of the most senior Democrats in Congress, have said defeating Donald Trump has become much harder and neither is sure of what action to take, according to the report. 

It comes after Mr Biden introduced Volodymyr Zelensky as his fiercest enemy “President Putin” on stage at the Nato summit in Washington. 

In a subsequent gaffe at a post-summit press conference, Mr Biden referred to his vice president Kamala Harris as “vice president Trump.”

Obama is said to be reluctant to go public with his concerns to avoid bolstering Trump. 

Mr Obama’s scepticism about Mr Biden’s chances of being reelected is “one of the worst kept secrets in Washington,” according to CNN. 

Mr Biden’s team believes Mr Obama may have had a role in a New York Times op-ed authored by George Clooney that called for Mr Biden to step aside.

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