Nikki Haley endorses Marco Rubio. Is that a big deal?

The South Carolina governor's endorsement is a boon for the Florida senator, but he's still got a long way to go with convincing voters he's authentic.

South Carolina’s popular Republican Gov. Nikki Haley is going to endorse Sen. Marco Rubio (R) of Florida for president at a Wednesday night rally, according to multiple news reports. With the Palmetto State’s GOP primary only three days away, is this a big deal?

Yes, yes it is. But by itself it may only help Senator Rubio survive, not leap into contention for front-runner status.

Governor Haley is a big prize, undeniably. She’s well liked in her state and has a national profile due to her response to President Obama’s State of the Union address. In that response she took obvious aim at Donald Trump by saying, “some people think that you have to be the loudest voice in the room to make a difference.” This earned her props from the establishment/donor class and other anti-Trump party elements.

And Rubio needs her backing. Until the most recent Republican debate he seemed to be emerging as the last, best hope of the establishment to counter the rise of Mr. Trump and Sen. Ted Cruz (R) of Texas. Then Gov. Chris Christie (R) of New Jersey ripped him up for repeating memorized talking points. He dropped to fifth in the New Hampshire primary, just behind fellow Floridian Jeb Bush.

But Rubio’s risen to fight again in South Carolina. He seems a match for the state’s more conservative and religious GOP electorate, and current polls show him in a virtual tie with Senator Cruz for second place. Haley’s endorsement – plus the backing of two other prominent South Carolina Republicans, Sen. Tim Scott and Rep. Trey Gowdy – could bolster his chances for Saturday’s vote. Rubio needs a second or clear third place finish if he’s going to remain a viable candidate.

Rubio’s gain is also Mr. Bush's and Cruz’s loss. Both Bush and Cruz had hoped to win Haley’s backing for themselves. It’s a bigger blow to the former than the latter; the Bush family has long-established ties to Haley. George W. Bush even complimented her during his South Carolina campaign speech for his brother earlier this week, saying of the Indian-American, “Thank goodness our country welcomed her parents when they immigrated here.”

A decisive Bush loss in South Carolina could be the end for his campaign. That would be a big help for Rubio, knocking out a main competitor for establishment and party elite backing.

But Rubio has yet to completely shake the effects of his robotic debate response. He’s still dogged by opposition campaign workers dressed as robots. The larger flaw they point up is the nature of his appeal, or the lack thereof. Rubio remains a great candidate on paper – young, articulate, and well versed in foreign policy – but there’s something about him that has yet to click with real voters. Perhaps it’s a quality of rehearsed artificiality. Perhaps they just see him as too young.

Haley’s endorsement won’t overcome that. A second-place finish for Rubio in South Carolina would be a real accomplishment. But he’ll have to start winning states at some point to win the nomination. When’s that going to happen?