COLUMBIA, S.C. - Democratic Lt. Gov. Yancey McGill temporarily took on executive authority Friday while Gov. Nikki Haley underwent surgery on her right arm, but he did not need to use it, a Haley aide told The Associated Press.

The Republican governor had outpatient surgery for "right radial nerve decompression" and returned home Friday morning, said spokesman Rob Godfrey.

Haley invoked a constitutional provision that says the lieutenant governor "shall have full authority to act in an emergency" in the case of the governor's temporary disability or absence.

McGill had that emergency authority for several hours, but no issues arose. Haley's surgery lasted about 30 minutes. She was back at the Governor's Mansion and resting by 10 a.m., Godfrey said.

Doctors attribute Haley's injury at least partly to her hand-signing 39,000 letters since taking office in January 2011, he said.

McGill, a 26-year veteran of the Senate, became lieutenant governor June 18. The Kingstree Democrat volunteered for the temporary post after the chamber's Republican leaders were unwilling to do so. The first Democrat in the No. 2 spot in two decades, McGill ascended into it after Lt. Gov. Glenn McConnell resigned. McGill will occupy the role only until the next elected lieutenant governor takes office in January.

McGill is the third lieutenant governor sworn into office since the 2010 election. Friday marks the first time Haley has transferred authority, though she routinely notifies the lieutenant governor whenever she leaves the state, Godfrey said.

Haley notified McGill of her impending surgery Thursday afternoon.

The lieutenant governor's spot is occupied at all largely because of the insistence of Haley and McConnell, who resigned to take his new job as president of the College of Charleston.

Sen. John Courson, R-Columbia, resigned his leadership post as the Senate president pro tem two weeks earlier in order to keep his Senate seat and not be forced to temporarily become lieutenant governor. Courson previously contended the lieutenant governor's spot could go unfilled until January.

But Haley said the state can't be left without a second in command that long.

"I need a lieutenant governor. I need someone that if I'm going to go out of state or if something happens to me, I can feel comfortable the state is in good hands," she said May 30. "I think the citizens of the state want that, too."

If the No. 2 spot had remained vacant, and Courson remained the Senate's leader, authority would have transferred to him Friday, as per the lines of succession.

No Democrat has had gubernatorial powers since former Gov. Jim Hodges left office in January 2003.

It's unclear when a South Carolina governor last transferred authority to the lieutenant governor. Former Gov. Mark Sanford famously did not do so in June 2009, when he disappeared to Buenos Aires, Argentina, for almost a week, returning to reveal an affair and resign as chairman of the Republican Governors Association.

McConnell, then Senate president pro tem, questioned whether Sanford broke the law by not transferring power to then-Lt. Gov. Andre Bauer. The House Judiciary Committee considered but ultimately declined to impeach Sanford. The full House instead voted to censure him, saying he was derelict in his duty and abused his power.

McConnell became lieutenant governor in 2012 after Ken Ard resigned and pleaded guilty to campaign spending violations.