The US donor network led by billionaire industrialist Charles Koch has signalled it will oppose Donald Trump’s bid to secure the 2024 Republican presidential nomination in the latest rift between wealthy conservative backers and the former president.

“The best thing for the country would be to have a president in 2025 who represents a new chapter,” Emily Seidel, chief executive of the network’s political campaign group, Americans for Prosperity, wrote in a statement posted online on Sunday. She added the group would support a candidate in the presidential primary “who can win”.

Announcing AFP’s intention to get involved in more primaries, Seidel said the Republican party was “nominating bad candidates who are advocating for things that go against core American principles. And the American people are rejecting them.” This left Democrats free to respond with “more extreme policies”, Seidel said.