A conservative-leaning political action committee backed by the influential Koch brothers' network is endorsing Nikki Haley for the Republican presidential nomination.

The Americans for Prosperity super-PAC says Haley is best positioned to beat former President Donald Trump in the primary election and President Biden in the general election.

In a letter addressed to "Grassroots Leaders, Activists, and Interested Parties," Americans for Prosperity Action says it's throwing its support behind the former South Carolina governor and United Nations Ambassador.

The statement says the Republican party has been choosing "bad candidates who are going against America's core principles," and that Democrats are responding with what it calls "extreme policies."

Americans for Prosperity, or AFP, says it believes nearly three-quarters of Republican voters are ready to move on from Trump. That's despite the former president leading among Republicans by a wide margin in national and key primary-state polls.

The AFP statement notes though that Haley has moved into second place in multiple polls and promises to spend on new mail, TV and online ads backing her.