Jeb Bush expressed disappointment that South Carolina Gov. Nikki Haley is backing presidential rival Sen. Marco RubioMarco RubioTop Trump officials push border wall as government shutdown looms Rubio defends Trump: 'This whole flip-flop thing is a political thing' Rubio: Shutdown would have 'catastrophic impact' on global affairs 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 ClintonPoll: 85 percent of Clinton supporters would vote for her again OMB director: Government shutdown not a 'desired end' Poll: Almost half say Trump off to poor start 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 TrumpReport: Senate's Russia probe understaffed Trump won't comment on Le Pen's advancement in French election Le Pen and the right wing hit a wall in French vote MORE in the lead, followed by Sen. Ted CruzTed CruzWarren builds her brand with 2020 down the road Trump wall faces skepticism on border No Congress members along Mexico border support funding Trump's wall 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.