Republican senator Mitt Romney on Wednesday called on Joe Biden and Donald Trump to “stand aside” for younger leaders and railed against the populist wing of his own party, as he said he would not seek re-election next year.

Romney, who is 76 and was the Republican candidate for president in 2012, announced the decision to end his political career in a pre-recorded video statement on Wednesday, saying: “At the end of another term, I’d be in my mid-eighties. Frankly, it’s time for a new generation of leaders.”

Speaking to reporters on Capitol Hill after the announcement, Romney said it would be a “great thing if both President Biden and former president Trump were to stand aside and let their respective party pick someone in the next generation”.