Haley to endorse Rubio
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South Carolina Gov. Nikki HaleyNimrata (Nikki) HaleyUS asks UN to respond to Iran supplying missiles to Yemeni rebels Trump packs a punch against North Korea as he embarks on Asia tour US upholds Cuba embargo in UN resolution vote MORE is endorsing Sen. Marco RubioMarco Antonio RubioOvernight Cybersecurity: What we learned from Carter Page's House Intel testimony | House to mark up foreign intel reform law | FBI can't access Texas shooter's phone | Sessions to testify at hearing amid Russia scrutiny Cornyn: Senate GOP tax plan to be released Thursday This week: GOP seeks to advance tax overhaul MORE (R-Fla.) in the Republican presidential race. 

The endorsement will be announced at a campaign event Wednesday evening. 
 
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Coming days before the South Carolina primary, the endorsement would be a major blow to former Florida Gov. Jeb Bush, who had hoped to secure Haley's backing.
 
The endorsement was first reported by The State newspaper and confirmed to the The Post and Courier.
 
Haley has emerged as a major voice in the state and nationally in the Republican Party, winning bipartisan praise for her handling of the massacre at a historic African-American church in Charleston last summer and subsequent debate over removing a Confederate flag at the statehouse.
 
Republicans leaders in Congress tapped Haley, who is in her second term as governor, to deliver the GOP response to President Obama's final State of the Union address this year, after she pushed back on GOP presidential front-runner Donald TrumpDonald John TrumpDems win from coast to coast Falwell after Gillespie loss: 'DC should annex' Northern Virginia Dems see gains in Virginia's House of Delegates MORE's rhetoric.
 
Haley had made no secret that she did not plan to endorse Trump, but it was an open question whether she would back Rubio or Bush. 
 
Bush has lagged in recent South Carolina polls, while Rubio has hung around third place in the Palmetto State. Other key figures in the state — including Sen. Tim ScottTimothy (Tim) Eugene ScottKey differences between the Senate and House tax plans Strange bedfellows on criminal justice reform could offer Trump a legislative win Senate GOP reveals different approach on tax reform MORE and Rep. Trey GowdyHarold (Trey) Watson GowdyControversial ‘hack back’ bill gains supporters despite critics Top Oversight Dem pushes back on Uranium One probe Overnight Cybersecurity: Manafort, Gates to remain under house arrest | Mueller said to be closing in on Flynn | 'Hack back' bill gains steam | Election security gets attention from DHS MORE — have thrown their support behind Rubio, while Sen. Lindsey GrahamLindsey Olin GrahamCNN to air sexual harassment Town Hall featuring Gretchen Carlson, Anita Hill Trump wrestles with handling American enemy combatants Flake: Trump's call for DOJ to probe Democrats 'not normal' MORE has supported Bush.
 
"If she is going to give an endorsement it would be the most powerful, meaningful one in the state," Bush told NBC's Peter Alexander during an interview on Tuesday.
 
Bush added if he didn't get the endorsement, "It sends a signal that I got to work harder."
 
Haley endorsed Mitt Romney in the 2012 GOP presidential race. Romney lost in South Carolina to Newt Gingrich that year, though he ended up winning the Republican nomination.
 
--This report was updated at 2:29 p.m.