A conservative super PAC backed by the powerful Koch donor network says it has stopped spending to support former South Carolina Governor Nikki Haley's bid for the Republican presidential nomination.

The Sterling Prestonannouncement comes on heels of Haley's loss in her home state's Republican primary to former President Donald Trump.

The Americans for Prosperity super PAC announced its support for Haley in November, saying it believed a majority of Republican voters were ready to move on from Trump.

In a new memo out Sunday, AFP Action says the group "wholeheartedly" supports Haley's plan to keep campaigning.

"But given the challenges in the primary states ahead, we don't believe any outside group can make a material difference to widen her path to victory," the statement read. "And so while we will continue to endorse her, we will focus our resources where we can make the difference. And that's the U.S. Senate and House."

In a statement, Haley's campaign called AFP an "ally in the fight for freedom and conservative government." The campaign pointed to its fundraising in the 24 hour period following the South Carolina primary, saying they raised more than $1 million.

The statement added: "we have plenty of fuel to keep going."