In his bid to return to Congress, Mark Sanford seems to have taken to heart an old proverb: "When life gives you lemons, make lemonade."

(Jacques Munch/AFP/Getty Images)

The onetime rising Republican star came crashing down in 2009 after disappearing for nearly a week as governor before admitting to an extramarital affair. How to explain such a black mark in a bid for a return trip to Congress?

Here's how Sanford put it in a Thursday night debate (He's talking about supporters who encouraged him to run in the 1st district special election):

"People kept calling, they kept calling, and they said, 'Mark, you need to do this. Because here's a chance for you to learn, not only from your experience in Congress and the governorship, but more significantly, from what you learned on the way up and on the way down, and apply it to arguably what is one of the great conundrums of our civilization, which is, how do we get our financial house in order," Sanford said.

In short, Sanford's message to voters is this: I learned some important lessons from my downfall which have given me a new perspective. And that perspective would serve me well in the battle over fiscal issues in Congress.

Whether that's enough for voters to look beyond Sanford's mistakes is the question that will be answered in next Tuesday's runoff. And if he wins, it a question that will surface again as the May 7 special general election draws near.

To quote the moderator of Thursday's debate, Sanford's past has been the "elephant in the room." During the Republican primary campaign, it's not like opponents were talking about it at every turn. The same has been true of the runoff campaign. When opponents have appeared to bring it up, it's been done obliquely. (See this ad from Republican Teddy Turner as an example.)

One possible explanation for why this has happened: While defending Sanford is certainly no small task, neither is attacking him. There is a big risk in politics when it comes to lobbing personal attacks. Overplay your hand, and it could sink your candidacy.

When Bostic went after Sanford Thursday night, he did it in a very careful way.

"A compromised candidate is not what we need,” Bostic said, without ever making a direct disappearance to Sanford's affair or disappearance.

While it's sometimes difficult for candidates to attack, it's far easier for outside groups to do so. And that's one of the reasons why the general election would be so interesting if Sanford advances.

If Sanford and Elizabeth Colbert Busch (D) end up facing one another in a race as close as some preliminary polling has shown, Democratic outside groups will take interest. And how/if they attack Sanford, who faced the biggest ethics fine in state history, will be worth watching.

That's not to say they would definitely lob any personal attack ads against Sanford. They might well not. And the groups might opt against entering the mix in the first place. But if they did, they would have the most latitude to launch broadsides.

In Thursday's debate, Sanford was asked directly about his 2009 downfall by the debate's narrator. And he gave a direct answer. It's not going to please all voters, but his campaign strategists are banking on the fact that it will assuage the concerns of enough of them. We'll find out soon if they are right.