Jeb Bush expressed disappointment that South Carolina Gov. Nikki Haley is backing presidential rival Sen. Marco RubioMarco RubioOvernight Energy: Senate panel clears Tillerson for State Senate panel votes to confirm Tillerson Overnight Defense: Trump nominates Air Force secretary | Senate clears CIA director | Details on first drone strike under Trump MORE (R-Fla.).
The campaign praised Haley in a statement and predicted she'd rally behind Bush when he wins the GOP nomination.
"That said, this race is about Jeb Bush being the only candidate in the field with a proven conservative record, detailed plans and the ability to defeat Hillary ClintonHillary Rodham ClintonTrump told leaders 'illegals' cost him popular vote Trump continues to insist voter fraud robbed him of popular vote Xavier Becerra confirmed as California attorney general MORE, which is what this party and country needs."
Haley's endorsement comes as Rubio looks to pull away from Bush ahead of Saturday's primary. Polls show Rubio hanging around third place, with Donald TrumpDonald TrumpTrump files paperwork to transfer businesses EPA freezes grant programs: reports Kellyanne Conway gets Secret Service protection MORE in the lead, followed by Sen. Ted CruzTed CruzTrump's America: Businessmen in, bureaucrats out When Trump says 'Make America Great Again,' he means it Booker is taking orders from corporate pharmaceuticals MORE (Texas) in second.
Rubio and Bush are battling to be the establishment standard-bearer and the Florida senator has touted the backing of several key South Carolina lawmakers.
Haley, a potential GOP vice presidential pick, is a rising star in the Republican Party.
She was tapped by party leaders in Congress to deliver the Republican response to President Obama's State of the Union address in January, where she criticized Trump.