Ed Miliband has been confronted by his old tweets describing Donald Trump as “a racist, misogynistic, self-confessed groper”.
BBC Breakfast presenter Jon Kay asked the energy secretary how he could possibly work with a man he had previously described in that way.
Trump will be sworn in for a second term as US president in January - four years after he was booted out of office by American voters.
He is at odds with the UK government over climate change, which he has previously described as “a hoax”.
Kay asked Miliband: “How do you build a relationship with a man who you described in the past as a racist, misogynistic, self-confessed groper?”
Speaking from the COP29 climate summit in Baku, Azerbaijan, Miliband replied: “Look ... you know ... I said things in the past. My job now, as a government minister, is to work with the new US administration.
“Donald Trump’s done lots of tweets in his time as well. I think what he will be interested in is serving a mandate from the American people. What we’re interested in is serving the mandate from the British people, and the British people have elected us to drive forward with this clean energy transition.”
But the presenter then asked him: “You made those comments I just quoted in 2016 when he was first elected as president.
“If you’d known that you were going to be in government in 2024 and he was about to be re-elected as president and you were going to have to deal with him on the issue of climate change, you probably wouldn’t have said them, would you?”
Miliband said: “Honestly, I think they’re irrelevant. I genuinely don’t think that Donald Trump is reading my tweets. I don’t have such a high opinion of myself.”