In 2009, Mark Sanford, a South Carolina Republican, was probably the best-known governor in America. Sanford, who served in the House of Representatives before winning the governorship, was in his second term when his staff couldn’t reach him or determine his whereabouts for several days. Sanford had said that he would be hiking the Appalachian Trail, but it emerged that he had travelled to Argentina, where he was conducting an extramarital affair. He was censured by the South Carolina House and had a messy, public divorce from his wife, but he managed to avoid resigning, and, in 2013, he won back his old House seat. At first, Sanford seemed as though he might be a typical Republican in the Tea Party-to-Trump era, but he became an outspoken critic of the President, predictably incurring Trump’s wrath. After Trump endorsed a Republican opponent, Sanford was defeated in the primary in 2018.

Now, Sanford may be seeking a measure of payback. He announced this week that he is considering challenging Trump for the Republican nomination in 2020. Sanford claims that his primary motivation is concern about the federal deficit. “We’re walking our way toward the most predictable financial crisis in the history of our nation,” he told CNN on Wednesday. Not long afterward, I spoke by phone with Sanford. During our conversation, which has been edited for length and clarity, we discussed why he wants to run as a single-issue candidate, his vote for the Trump tax cuts, and his feelings about Trump’s racism.

Why do you want to be President?

Because I think we are nearing the greatest financial collapse in the history of our nation, and, if we don’t start dealing with and talking about debt and deficit spending, it is coming our way.

Do you think something has changed in the Republican Party about spending in the last couple of years?

Yeah, we have quit talking about it. Financial conservatism or financial realism has always been a cornerstone of the Republican Party and the conservative movement. And yet in the age of Trump that has seemingly gone out the window. I think there are any number of folks out there—in the wilderness, if you will, as I am—saying, “Look, we like what Trump has done with regard to judicial appointments, we like what he has done in terms of trying to do something on our border. But we also have to have financial sanity.” And that is something that is not part of the mix of the Republican Party of late. It is not part of the mix of the Democratic Party. It is not something being talked about in Washington these days.

Did you consider yourself a fiscal conservative during your latest stint in Congress?

I did. And, more important, a whole host of different ratings agencies have labelled me as such, so it doesn’t matter what I think or what I say. It does matter that third-party organizations have put me in that group.

Why did you vote for the Trump tax cut in 2017?

Well, as you know, or as you might know, that was originally a Democratic proposal.

The Trump tax cut?

Yeah, the basis of it was Ron Wyden’s bill, a Democrat on the West Coast who said we have to become more competitive with regard to corporate tax rates. [Aspects of the tax bill were similar to parts of a bill that Wyden co-sponsored; Wyden called Trump’s bill a “middle-class con job.”] I think we absolutely do. If you look at where we were relative to the rest of the industrialized world on corporate tax rates, we weren’t competitive. And so it was a bipartisan idea to say, “Let’s look at ways of becoming more competitive so that we can indeed grow the economy.”

It was not some of the things the Republicans described it as. I made national news when I said that was not a middle-class tax cut. It was fundamentally a corporate tax reduction and restructuring bill. So I think both sides overplayed it. The Democrats said it would blow a hole in the deficit, and that’s not true, either.

The C.B.O. projected that it will add around $1.9 trillion to deficits over ten years, even after allowing for any growth effects. You disagree with that?

That’s completely true. But look at the aggregate numbers. What is the number we are going to spend over the next ten years at the federal government?

I don’t have the number on me.

It’s forty-three trillion dollars. With the tax cut, we are at $41.5 trillion. That’s a 3.5-per-cent difference over the next ten years. So will it add a little bit? Yeah. But if I were to talk to you about your family budget, and you said, over the next ten years, there is going to be a 3.5-per-cent difference on one scenario versus another, you wouldn’t say, “It completely cripples me and blows up the deficit.” You would say, “Well, it’s a 3.5-per-cent difference.” [The forty-three-trillion-dollar number was the expected ten-year federal revenues when the bill was signed. The updated numbers are forty-six trillion dollars in revenues and fifty-seven trillion dollars in outlays, or spending. The tax cut, now expected to cost at least a trillion and a half dollars, thus represents around fifteen per cent of the projected deficit over the next decade.]

Right, but you are talking about what you said was one of the greatest crises to face our nation, and this legislation—more than any piece of legislation that has come up in the Trump era—which you voted for, is the biggest deficit expander.

Wait, wait, wait, I don’t know what you just said.

I said that you said this is a crisis for our nation, so it seems like even if this isn’t the only thing contributing to our debt and yearly deficits, it is still the single biggest contributor of any bill in the Trump era. And you voted for it.

Well, the Trump era is two years old. I think you have to have a longer continuum when you look at competitiveness in the country. I would certainly cede you the point that you could make the argument that it would contribute to it. But you could make the equal argument that, if you do nothing, you will contribute to the deficit, because if we do nothing to grow our economy, we are going to be toast with regard to debt and deficit issues. So you can approach it from both sides of the ledger, and I think it is indeed important to look at both sides of the ledger.

I was just quoting the C.B.O., which took into account growth effects.

Sure. Sure. Sure.

Deficits went up in the Reagan years and the George W. Bush years. Do you think this is something grassroots Republicans actually care about?

I know they care about it. I have spent a lot of time in elected office over the past twenty-plus years. It is less of a conversation in Washington than at kitchen tables around the country. You talk about a small business or putting together a family budget; they talk about financial realism. People are absolutely aware of the fact that we have lost financial reality in Washington, and I think it frustrates them. And whether I run or start up an advocacy group to bring some measure of focus to this issue, I think it is not part of the debate in Washington but needs to be.