Americans for Prosperity, a fundraising organization established by powerful conservatives Charles and David Koch, is not endorsing former President Donald Trump in the 2024 Republican primary, the organization hinted in a memo Sunday.

«The best thing for the country would be to have a president in 2025 who represents a new chapter,» says a letter from the organization’s executive director, Emily Seidel. But the memo did not mention Trump by name, leaving open the possibility of an endorsement later.

The move could spell trouble for Trump if it alienates AFP’s wealthy conservative donor base from his campaign. He is the only major-party candidate to have announced a 2024 run so far, though a cast of potential GOP challengers have publicly teased possible campaigns.