The influential group, which pushes for tax cuts and less government regulation, has made clear that beating former President Trump in the Republican nominating contest is a top priority, arguing that he would lose the November election to President Joe Biden. The Democrat beat incumbent Trump in the 2020 White House race.

In addition to controlling tens of millions of dollars for campaign spending, the Koch-affiliated Super PAC known as Americans for Prosperity Action, or AFP Action, has thousands of staffers throughout the country who will now promote Haley among potential voters.

Among Haley's main weaknesses, according to her campaign operatives, has been a relatively underdeveloped network of campaign workers and allies in the early voting state of Iowa.

It is far from clear that the AFP endorsement will be a game changer, given that Trump leads his Republican rivals by more than 40 points in most national polls. About 10% of Republican primary voters support Haley, according to a polling average maintained by poll-tracking website FiveThirtyEight.

But the endorsement could tip the scales in favor of Haley in a tight battle with Florida Governor Ron DeSantis for the No. 2 slot. Around 13% of primary voters support DeSantis, according to FiveThirtyEight.

It could also help her persuade other major donors to get behind her. Many big-dollar donors have been considering supporting Haley for months, but have held off amid concerns she is simply too far behind Trump.

"The Kochs have a tremendous following," said Texas-based Republican donor Fred Zeidman, a top Haley fundraiser.

DESANTIS PUSHBACK

The group said its internal polling indicates Haley is in the best position to defeat Trump in the Republican primary. It also "consistently shows" that Haley is the strongest candidate by far to beat Biden in a general election, it said.

"We would support a candidate capable of turning the page on Washington's toxic culture – and a candidate who can win. And last night, we concluded that analysis," AFP Action said in a statement.

DeSantis supporters have disputed those assertions, saying he is better positioned to siphon supporters away from Trump than Haley is. Haley is beating DeSantis, however, in some of the states that are first to select a Republican nominee.

"Every dollar spent on Nikki Haley's candidacy should be reported as an in-kind to the Trump campaign," DeSantis spokesman Andrew Romeo wrote on X on Tuesday.

Trump campaign adviser Steven Cheung responded to the AFP endorsement with a swipe at Haley's foreign policy positions. AFP Action has endorsed a "pro-China, open borders, and globalist candidate," Cheung said.

While Haley, who was U.S. ambassador to the United Nations under Trump, has staked out a significantly more hawkish position on China than her 2024 rivals, the DeSantis and Trump camps have criticized her for welcoming Chinese investment into South Carolina while governor.

The Koch endorsement marks a turnaround from the previous two presidential cycles, which the Kochs broadly sat out.

DeSantis had been under active consideration for an endorsement, but his disappointing campaign turned off AFP Action, two sources with knowledge of those deliberations said.

AFP Action raised more than $70 million to spend on political races, an official with the group said in July. Super PACs are allowed to raise and spend unlimited sums supporting candidates as long as they don't coordinate with campaigns.

Emily Seidel, a senior adviser at AFP Action, told reporters on Tuesday the group would dedicate significant resources to getting out the vote for the Republican primaries, including encouraging general election voters to vote in the primaries for the first time.

During the 2022 congressional elections, AFP Action says it made more than 2 million phone calls, knocked on 5.5 million doors and sent more than 69 million pieces of mail.

The Democratic National Committee said Haley checks all the Koch group's boxes: "slashing taxes for the ultra-wealthy, gutting Social Security and Medicare, and ripping health care away from millions of Americans.