Where is Gov. Sanford, and Who’s In Charge of SC?

ABC News' Elizabeth Gorman reports:

The first lady of South Carolina said that her husband, Gov. Mark Sanford, has been gone for several days, and she did not know where he was.

His cell phone was turned off, and he wasn't answering texts or phone messages for four days, The State, a South Carolina newspaper, reported.

"The governor put in a lot of time during this last legislative session, and after the session winds down it's not uncommon for him to go out of pocket for a few days at a time to clear his head," Sanford spokesman Joel Sawyer wrote to ABC News.

"Before leaving last week, he let staff know his whereabouts and that he'd be difficult to reach. Should any emergencies arise between the times in which he checks in, our staff would obviously be in contact with other state officials as the situation warrants before making any decisions," he wrote.

His wife Jenny Sanford told the Associated Press she is not concerned, and that he'd said he needed time away from home to write.

But Sanford's absence does raise concerns for Sen. Jake Knotts, R-SC, who contacted authorities as early as Saturday when he heard that Sanford couldn't be reached.

"I want to know immediately ­ who is running the executive branch in the governor's absence," he said.

The South Carolina constitution states that “in the event of the temporary absence of the Governor from the State, the Lieutenant Governor shall have full authority to act in an emergency.”

South Carolina Lieutenant Governor Lt. Gov. Andre Bauer said he wasn't aware of Sanford's plan.

"Our job is to serve if needed. We have talked to the governor's office, and they tell us they know where the governor is, and that they will call us if needed. They have told us if anything occurs, they will call us," a spokesperson for Bauer told ABC News.

Although Gov. Sanford is not in touch, he still managed to Twitter on Monday. His tweet read: "SC's government structure fundamentally flawed." It linked to an op-ed he wrote that was published on Sunday.

It was his staff, and not Sanford, who tweeted.

UPDATE: From Sanford's office late Monday night: "The governor is hiking along the Appalachian Trail. . . . I want to emphasize
that this isn't something that either staff or Mrs. Sanford is concerned about.
As we said earlier today, it isn't unusual for the governor to be out of pocket
for several days after the legislative session. We knew he would be difficult to
reach, and that he would be checking in infrequently."

UPDATE: Sanford's office said he called and checked in with his office this morning. "It would be fair to say the governor was somewhat taken aback by all of the interest this trip has gotten," Sanford's spokesman said.  Sanford is planning to be back in the office tomorrow, "given the circumstances and the attention this has garnered," the spokesman said.