COLUMBIA - Lt. Gov. Glenn McConnell plans to resign his post Thursday and said that the state's Constitution requires that a new lieutenant governor take his place - a stance that is at odds with the man next in line.

McConnell, a longtime Charleston senator and the incoming president of the College of Charleston, told the Post and Courier late Monday that he would wrap up his affairs and send a resignation letter to the appropriate officials by the end of Thursday.

The lieutenant governor says he needs time to transition to his new job and that the politics around a bill that would establish a newly-expanded University of Charleston have made his position untenable since he presides over the S.C. Senate. He supports the bill and does not want senators to claim bias about his procedural rulings.

The president pro tempore, or leader of the Senate, should know that there is risk involved with the position, he said.

McConnell said he was at the height of his career as the president pro tempore and key committee chairman when he was forced to resign his seat to become lieutenant governor after former Lt. Gov. Ken Ard resigned in 2012.

"You fundamentally have two choices: step up or step out," McConnell said. "You've got to do one of the two. I was confronted with the same dilemma he is in. I'm not going to criticize him. You can enjoy the power of the position, but the circumstances are such you may have to pay for it."

Sen. John Courson, R-Columbia, says he will not resign his seat to become lieutenant governor. The state has gone without a lieutenant governor six times, most recently from 1965 to 1967. Gov. Nikki Haley also recently called on Courson to step up to the position.

The absence of a lieutenant governor, McConnell said, causes constitutional problems because a member of the Legislature cannot exercise the same powers as someone in the executive branch.

The lieutenant governor oversees full-time staffers, as well as the Office on Aging. McConnell asked who would ratify bills, as well as approve employee pay or emergency grants for seniors applied for through the aging office. He also said that Gov. Haley notifies him whenever she is out of the state or country should someone need to step into the governor's role. The chief role of the state's No. 2 post is to act as governor if it became necessary.

"There's got to be a lieutenant governor. You can't have a president pro tempore with no lieutenant governor," McConnell said. "If the president pro tempore exercises the power of the lieutenant governor, he becomes the lieutenant governor."

Courson said in an interview Monday that constitutional scholars disagree. Asked if he would step aside as president pro tempore, he said, "That really hasn't entered my mind. It could, but it hasn't entered my mind."

Courson said he made a campaign promise not to take the job if it was a short-term post when it was brought up by his opponent in 2012. He said no one can force him to take the job.

"I am a Marine by training," he said. "I'll do it on my own volition."

Haley has said the state can't be left without a second in command until January. "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. "I think the citizens of the state want that, too."

Courson said that under the state's lines of succession, he'd still be the person to assume the governor's duties, should something happen. McConnell said he would not be in Columbia Tuesday and would not preside over the Senate if a bill that he has backed establishing a newly-expanded University of Charleston was still being considered on Wednesday or Thursday, the last days of the legislative session.

The Associated Press contributed to this report.

Reach Jeremy Borden at 708-5837.