5:30 PM UPDATE:

South Carolina Gov. Mark Sanford responded in a letter to Lt. Gov. Andre Bauer, who earlier today called for him to resign.

“What I say in this letter is that I’m not gonna be railroaded out of this office by political opponents or folks that were never friends of mine in the first place,” Sanford told reporters at an afternoon news conference. “A lot of what’s going on is just pure politics plain and simple.”

Gov. Sanford denied media reports suggesting he had purchased first class tickets at taxpayer expense and said his use of state aircraft was a fraction that of previous administrations.

The governor added he had done some of his own investigation into the travel habits of other South Carolina lawmakers.

“Turns out folks were flying back and forth on the Concorde from Europe in days past,” he said. “It turns out that members of the General Assembly were flying on business class tickets.”

While Sanford said escaping the media and political frenzy surrounding him would be “something close to heaven on earth,” he insisted he had too much work do on important issues, such as jobs and the economy, to step down now.

“What is unequivocally clear is that the end of my time in politics will be at the end of 16 months. But I do want to make the most of it,” he said.

2:45 PM UPDATE:

Calling on South Carolina Gov. Mark Sanford to resign, Lt. Gov. Andre Bauer said:

“The serious misconduct that has been revealed along with lingering questions and continuing distractions make it virtually impossible for our state to solve the critical problems we’re facing without a change in leadership.”

The governor’s office issued a news release announcing that Sanford would hold a media availability at 3:30 PM ET “to respond to statements made by Lieutenant Governor Andre Bauer earlier today.”

12:36 PM:

South Carolina’s lieutenant governor is calling on his embattled governor to resign.

Lt. Gov Andre Bauer (R) made the announcement at a noon news conference at the South Carolina statehouse.

Gov. Mark Sanford (R) has been under fire since June when he was missing in action for five days — only to reveal that he had been in Argentina, visiting a woman with whom he had been having an extramarital affair.

While the governor’s admission angered social conservatives within his party, his seemingly frugal ways had made him a darling among fiscal conservatives. But even that has been unraveling in recent weeks.

Sanford is under intense scrutiny in the media for allegedly using state planes for personal and political trips and for allegedly flying first class at taxpayer expense.

If Sanford were to resign, Bauer would fill the remainder of the governor’s term.

Under South Carolina’s state constitution, the governor and lieutenant governor are elected separately. This creates an often contentious relationship between the two offices, which in some previous years have been held by different parties.

Although the current governor and lieutenant governor are both Republicans, Sanford and Bauer have often butted heads.

Sanford is term-limited and approaching his final year in office.

Bauer is considered a likely candidate for governor. However, he renewed his pledge that, if Sanford were to resign, he would not seek election to that office in 2010.

Sanford had no immediate comment in reaction to Bauer’s announcement. However, the governor’s press secretary says he expects to issue a statement later today.

(Photo Credit: Associated Press)