Americans for Prosperity Action, the political wing of the influential and deep-pocketed fiscally conservative network founded by the billionaire Koch Brothers, is endorsing Nikki Haley for the 2024 Republican presidential nomination.The group, which has pledged to spend tens of millions of dollars to help push the Republican Party past former President Trump, made its announcement Tuesday morning in a memo.AFP Action said that “it is proud to be throwing the full weight and scope of its grassroots operation behind Nikki Haley to help her become the next President of the United States. That effort will begin with a multimillion dollar ad campaign launching this week in all early and several Super Tuesday states calling on Americans to unite behind Haley’s positive vision to turn the page on today’s broken politics and move our country forward.”THE FINAL COUNTDOWN: TRUMP HOLDS COMMANDING LEAD WITH 50 DAYS TO GO UNTIL IOWA CAUCUSES Former ambassador to the United Nations and former South Carolina Gov. Nikki Haley, a 2024 Republican presidential candidate, speaks at a town hall in Hooksett, New Hampshire, on Nov. 20, 2023 (Fox News – Paul Steinhauser)Haley, the former two-term South Carolina governor who later served as ambassador to the United Nations in the Trump administration, launched her 2024 GOP presidential campaign in February. She’s enjoyed momentum in the polls in recent months, thanks in part to well-received performances in the first three GOP presidential primary debates. GAME ON IN IOWA AS DESANTIS AND HALEY BATTLE FOR SECOND PLACE BEHIND TRUMPHaley has leapfrogged Florida Gov. Ron DeSantis for second place in New Hampshire — which holds the first primary and votes second in the Republican nominating schedule — and in her home state, which holds the first southern contest. And she’s pulled even with DeSantis in some of the latest polls in Iowa, whose caucuses kick off the GOP nominating calendar on Jan. 15.But Haley and DeSantis remain far behind Trump, who continues to hold a commanding lead over the rest of the field as the former president makes his third straight White House run. Republican presidential candidate and former President Donald Trump speaks during a rally, Saturday, Nov. 18, 2023, in Fort Dodge, Iowa. (AP Photo/Bryon Houlgrave) (AP Photo/Bryon Houlgrave)The AFP Action endorsement should help Haley, whose campaign lacks the grassroots outreach and organizational strength that DeSantis enjoys, due to the major assist from the DeSantis-aligned super PAC Never Back Down.The endorsement by AFP Action will likely support Haley with the group’s powerful direct-mail and field operations, as well as a major ad blitz in the early voting states. In the 2022 midterm election cycle, the group knocked on roughly 5.5 million doors, made 2 million calls, and sent out nearly 70 million pieces of mail on behalf of candidates it was backing.CLICK HERE TO GET THE FOX NEWS APP AFP Action senior adviser Emily Seidel, who called her group “a true grassroots organization,” highlighted that “when we announced our decision to engage in our first ever Republican presidential primary, we made it clear that we’d be looking for a candidate who can turn the page on our political dysfunction — and win. It’s clear that candidate is Nikki Haley.”Seidel pledged that “we will be doing everything we can to help make her the next President of the United States.” Haley, reacting to the endorsement, said the group’s “members know that there is too much at stake in this election to sit on the sidelines. This is a choice between freedom and socialism, individual liberty and big government, fiscal responsibility and spiraling debt. We have a country to save, and I’m grateful to have AFP Action by our side.” Florida Gov. Ron DeSantis, a 2024 Republican presidential candidate, speaks at a town hall in Manchester, New Hampshire hosted by the DeSantis-aligned super PAC Never Back Down, on Nov. 21, 2023 (Fox  News – Paul Steinhauser)The DeSantis campaign, reacting to the news, argued that the AFP Action endorsement of Haley will only bolster Trump as he aims to win the GOP presidential nomination.”Congratulations to Donald Trump on securing the Koch endorsement. Like clockwork, the pro-open borders, pro-jail break bill establishment is lining up behind a moderate who has no mathematical pathway of defeating the former president. Every dollar spent on Nikki Haley’s candidacy should be reported as an in-kind to the Trump campaign. No one has a stronger record of beating the establishment than Ron DeSantis, and this time will be no different,” DeSantis campaign communications director Andrew Romeo said in a statement.Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub. Paul Steinhauser is a politics reporter based in New Hampshire.Â