Liz Truss and Joe Biden are set to clash over tax cuts for the rich when the pair hold their first face-to-face talks since she became prime minister.
The two leaders will meet at the United Nations general assembly, which is taking place in New York, tomorrow.
But deep splits between the pair over economic policy burst into the open on the eve of the historic discussion.
Truss made clear that she was prepared to slash taxes - including income tax - to boost economic growth.
But almost at the same time, Biden tweeted his opposition to so-called “trickle down” economics - the theory that reducing taxes for the well-off eventually benefits the whole country.
Kwasi Kwarteng will deliver a mini-budget on Friday cancelling the rise in national insurance contributions and scrapping plans to increase corporation tax.
He is also expecting to end the cap on bankers’ bonuses in an attempt to make the UK more attractive to global talent.
Asked by the BBC if she was happy to see “the rich get richer”, Truss said: “If that means taking difficult decisions, which are going to help Britain become more competitive, help Britain become more attractive, help more investment flow into our country, yes, I’m absolutely prepared to take those decisions.
“Because what I care about is I care about our country being successful, and everyone in our country, wherever they live, wherever they’re from, having those opportunities.”
The PM also said she was willing to do “unpopular things”, adding: “We do have to take difficult decisions to get our economy growing.
“We have to look at our tax rates. So corporation tax needs to be competitive with other countries so that we can attract that investment but ultimately, the reason I’m doing that and the reason the chancellor is doing that is because we want people across this country to have those opportunities. That’s why we’re doing it.”
Truss and Biden are already at odds over the Northern Ireland protocol, with the US administration warning that a trade deal with the UK depends on the Good Friday Agreement being protected.
The PM has been forced to admit that a trade deal is years away, despite the government previously claiming an agreement was on the verge of being struck.