US President Joe Biden joked about Donald Trump and his own age at an annual media dinner on Saturday — before unloading deadly serious criticisms of his rival in November’s election.

“One candidate’s too old and mentally unfit to be president,” the 81-year-old Democrat quipped at the Gridiron Club in Washington. “The other guy’s me.”

Democrat Biden was making his first speech as president at the annual white tie gala for the US media and political elite, an event that Republican former president Trump addressed in 2018.

Biden is trailing in a number of polls and faces voters concerns about his age, which he has tried to address by highlighting 77-year-old Trump’s recent verbal slip-ups.

In his remarks, Biden took a swipe at Republicans in Congress who have launched an impeachment inquiry into his son’s business dealings, saying they would “rather fail at impeachment than succeed at anything else.”

He added that Irish Prime Minister Leo Varadkar, sitting at the head table with Biden on the eve of St. Patrick’s Day “took one look at Congress and he asked for another Guinness.”