South Carolina Gov. Nikki Haley officially endorsed Florida Sen. Marco Rubio ahead of Saturday’s primary in the Palmetto State.
The endorsement, first reported by The State and other state media, was announced at an event in Lexington County.
"I wanted someone with compassion and conviction to do the right thing," Haley said on Wednesday.
"Ladies and gentlemen, if we elect Marco Rubio, every day will be a great day in America," she said.
Rubio said that Haley embodied "everything" he wants the Republican Party to be about.
"Nikki Haley is a very serious governor about issues confronting not just her state, but the country," he told Fox News' Greta Van Susteren in an exclusive interview after the endorsement.
Haley told Van Susteren she made phone calls to Jeb Bush and Ted Cruz earlier in the day on Wednesday to inform them she would not be endorsing them.
“I made a phone call out of respect,” Haley said. “Our country was blessed they took the time to run for president.”
Haley's endorsement was considered the most coveted among South Carolina politicians, in part because she has very high approval ratings in the state. She joins Sen. Tim Scott and Rep. Trey Gowdy in endorsing Rubio.
The state's first female and first minority governor said just Tuesday that she may not endorse this cycle.
Haley has been critical of frontrunner Donald Trump, and used her response to President Obama’s State of the Union in January to warn against the kind of rhetoric Trump has used.
Haley endorsed Mitt Romney a month before South Carolina's 2012 presidential primary and campaigned with him. Romney lost to Newt Gingrich, breaking the state's three-decade tradition of backing the party's eventual nominee.
The Associated Press contributed to this report.