Following the release of the interview, South Carolina Attorney General Henry McMaster -- considered a frontrunner in the 2010 gubernatorial race -- called for an investigation and said he requested the State Law Enforcement Division to review all of Sanford's travel records to see if any laws were broken or if any state funds misused.
However, Reggie Lloyd, director of the agency, said Tuesday it is not a criminal investigation and so far there has been no evidence suggesting that there was wrongdoing.
Before Tuesday, both McMaster and Lloyd dismissed the prospect of an investigation.
Some Republicans have stayed on the sidelines in the calls for Sanford's resignation.
House Speaker Bobby Harrell, a Republican who would be the chair if the South Carolina legislature forced Sanford to resign, says calls to remove Sanford should wait until results of the state investigation.
"Talking about impeachment is premature at this point," said Harrell's communications director, Greg Foster. "He's encouraged by the investigation and would like to see the results of that and see if public funds were misused, but he's standing by his statement [that Sanford is the one who needs to decide if he can be an effective chief executive]."
The outcome of the investigation has significant political implications. McMaster is one of the top contenders for next year's gubernatorial race along with Lt. Gov. Andre Bauer, who would take over if Sanford resigns or is impeached.
"If he [McMaster] has this investigation, he gets more publicity and name recognition if he does a good job," Robert Oldendick, an executive director and professor at the University of South Carolina, told ABCNews.com. "The downside is that if Sanford does leave office, and Lt. Gov. Bauer takes over, it gives him 15 to 16 months of incumbency leading into the race and that will be to his advantage in terms of media and name recognition."
Some Democrats say the investigation is merely for show.
"It ain't big at all," J. Todd Rutherford, a Democrat in the South Carolina House of Representatives, told ABCNews.com. "He [McMaster] just did it because Sanford embarrassed himself and others. Nothing new has come out about state money."
Rutherford, who called for Sanford to resign shortly after the governor announced his affair, said the investigation is unlikely to prove anything because the governor used cash on his trips. He insists Sanford should resign because he broke the law when he failed to inform his lieutenant governor that he was leaving the country.
"He should resign because of what he did when he disappeared," Rutherford said. "There are no state employee guidelines that allow for the employee to be gone for five days [without notification]."
Republicans say an impeachment in the legislature is also unlikely.
"My view of the impeachment possibility or prospect is, we're going to have to put our hands on some very hard evidence that he has abused his position in the extramarital affair," Martin said. "Just looking at the makeup of the legislature and how difficult of an objective that would be and the tremendously excruciating ordeal it would put the state through ... Unless we get some further hard information about public money or abuse of position ... I just simply don't know about that. I think his best course is to resign."