Interviews with leading GOP fundraisers, donors and outside conservative groups reveal that Trump is so deeply disliked by large parts of the Republican Party’s donor community that he will have trouble winning their favor in a general election. Then, he’d need more than $1 billion to defeat the money machine of the Hillary Clinton campaign, the presumptive Democratic nominee.

“Trump has insulted most of the contributors and fundraisers in the country,” said Mel Sembler, a former Republican National Committee (RNC) finance chairman and board member for the super-PAC Right to Rise, which raised and spent more than $100 million in support of Jeb Bush’s unsuccessful primary campaign.

The finance chairman of the Republican Governors Association, Fred Malek, said Trump has perilously little time to build the kind of fundraising apparatus required to compete nationwide in a general election.

“Many major donors are very uncertain about who the nominee’s going to be, so he can’t really gear up much of a fundraising operation until after the convention,” Malek told The Hill. “Should he become the nominee, I don’t think there’ll be a great deal of enthusiasm.”