"We've been counted out more than a few times," said Barrett in a statement Tuesday night.
His comments came hours after polls closed Tuesday in a primary election in which GOP candidates carefully cultivated images as outsiders shaking up the establishment or fighting the federal government.
"But yesterday took the cake: I read two stories on our race previewing the final 24 hours. One said there wouldn't be a runoff. The other says there was gonna be a runoff all right. Just without me in it."
Thanking supporters, the four-term congressman added, "We beat the odds, we defied the experts, we made the run-off and now we've got two weeks to work hard ... ."
On Tuesday Haley collected 49 percent of the vote, about 1 percent shy of being the party's nominee and preempting a June 22 runoff. Barrett, with the next-highest vote total, received 22 percent in the four-way contest. The winner will face Democrat Vincent Sheheen, a state senator from Camden, in the Nov. 2 election.
Less than a month ago, it was Haley, a 38-year-old state legislator who was the long shot -- and making the most of it.
It all changed for the married mother of two on May 14.
That's when Republican vice-presidential nominee Sarah Palin held a rally for Haley on the state Capitol steps, marking a dramatic turning point for Haley's candidacy. Earlier former state first lady Jenny Sanford had also campaigned for the Lexington Republican.
Palin had noted that although her husband Todd could not attend the Columbia rally her spouse was, "wishing his very best to Nikki, knowing what she's probably going through, kind of being the underdog, being the fighter, being the winner that she is ... . We went through the same thing."
Haley's poll numbers shot up after the Palin endorsement, and two men stepped forward claiming they had an extramarital affair with Haley. Next a state senator referred to Haley, an Indian American, and President Obama, as a "raghead," a slur aimed at people of Arab descent.
At least one male lobbyist and a male legislator said it was the best thing that could have happened to her.
Still, Haley's challenge now is to retain her scrappy-outsider appeal, despite handing off her underdog status to Barrett.
On Wednesday, Rep. Vida Miller, D-Pawleys Island, who chairs the S.C. Women's Legislative Caucus, said the sexual allegations and the ethnic slur were probably the product of both Haley's gender and her front-runner status.
"I do think it's been a contributing factor to her overall success," said Miller. "I do think folks are sympathetic."
Reach Sarita Chourey at firstname.lastname@example.org or (803) 727-4257