"Officially we're going to announce tomorrow, and then it's off to the races," Sanford told the conservative National Review. "What I'd like to do is take all that I've learned in my time in Congress and my governorship, on my way up and on my way down, and apply it to what is probably the most important debate that we will have in regard to the future of our country. I'm running because I care deeply about spending, and the mathematical impossibility of us continuing down the path we're on."

Sanford, once a rising star in the GOP, saw his career unravel when he admitted to an affair with an Argentine woman in 2009 after initially claiming he was off hiking the Appalachian Trail. He's now trying to make a comeback despite remaining best-known for those indiscretions. His ex-wife, former South Carolina First Lady (R), said on Monday that he would have "a number of questions to answer" on the issue if he ran.

When asked what he'd tell voters concerned about the missteps, Sanford defended himself against some of the financial ethics charges brought forward by the statehouse — but apologized for what happened with his marriage.

"You have to, in essence, look under the hood. There's a larger philosophical question. In life we're all going to make mistakes, we're all going to come up short. The key is, how do you get back up and how do you learn from those mistakes?" he said. "I think that the bigger issue is, don't judge any one person by their best day, don't judge them by their worst day. Look at the totality, the whole of their life, and make judgments accordingly."

As to the other part, the dissolution of a marriage, it's tragic in every sense of the word. I certainly made mistakes. Nobody's going to bat a thousand," he continued. "Tragically, a lot of people get divorced in the United States of America, and I suspect many of them have missteps along that path. All you can do is try to make it as right as you can with the people in your life and lift your head up and try to move forward."

Sanford argued that he'd be the strongest candidate to take on deficit spending.

"I think if you look at the almost 20 years in the larger federal or state debate, what you see is an amazingly consistent record on looking out for the taxpayer and trying to impact that which I think worries a lot of people right now, that spending locomotive that we have going in Washington right now," he said.

A number of Republicans will run against Sanford for the seat, which until recently was held by now-Sen. Tim ScottTimothy (Tim) Eugene ScottSchumer: 'I totally believe' Durbin over Trump Graham: 'It's pretty embarrassing' when children can't listen to the news Durbin spokesman: GOP senators have ‘credibility problem’ MORE (R-S.C.). While he's expected to make the primary runoff, whether he can win the seat may be determined by who he faces in the two-week runoff.