TERRY GROSS, HOST:

This is FRESH AIR. I'm Terry Gross. If you want to know what the Republicans would do if they win in November, the person to understand isn't necessarily Mitt Romney, it's Paul Ryan. That's what Ryan Lizza writes in his article "Fussbudget: How Paul Ryan captured the G.O.P." It's published in the current edition of the New Yorker.

Congressman Paul Ryan of Wisconsin is the chair of the House Budget Committee, and nearly every Republican in the House and the Senate has voted in favor of some version of his budget plan. Ryan's goals include radically curtailing the government's role and its spending on social welfare programs like Medicare and Medicaid.

Lizza's article describes Congressman Ryan's background, how he developed his conservative views and how he's become a leader in his party. Ryan Lizza is Washington correspondent for the New Yorker and is covering the presidential campaign. Ryan Lizza, welcome back to FRESH AIR. You say that Congressman Ryan is remaking the Republican Party in his own image. What is that image? What are his core political and social beliefs?

RYAN LIZZA: I say he's remaking the Republican Party because in a very short period of time, he convinced all of his colleagues in the House or almost all of them and almost all of his colleagues in the Senate to vote for a set of ideas that just a few years ago, as recently as I think 2008, he could only get, you know, eight co-sponsors for.

That's sort of the heart of the story is how did he do this in just such a short period of time. And so just, you know, to get into the nitty-gritty of the policy, what you hear commonly described as the Ryan budget, right, you're going to hear this phrase a lot in this political campaign, the Ryan budget, this is the Republican policy manifesto, right. This is the - this is what Republicans in Congress have been talking about running on and proposing as the alternative to the Barack Obama policy agenda. And it took a long time for it to take shape.

So it starts with a radical alteration of Medicare, where if you're 55 or younger, when you enter the Medicare program, which is the government health care program for folks over 65, so if you're 55, in 10 years, if this policy were adopted, Medicare would no longer be a government insurance program. What you would get is a lump sum from the government, and you'd go out onto the private market and buy your own health care. You know, the criticism of that is that you wouldn't have enough money to pay for a health care plan under that design.

GROSS: So what else is in the budget plan that Ryan has proposed that you think helps define who he is politically?

LIZZA: Yeah, so a few big things. Medicare, radical reform of Medicare, fairly radical changes in Medicaid that would amount to cutting Medicaid, which is the health care program for the poor, by a third. A very - new set of large tax cuts that amount to $4 trillion over 10 years and then unspecified - so we don't know the exact programs he would cut, but big, major cuts to what's known as the discretionary portion of the federal budget, you know, the portion that pays for everything from national parks to meat inspection.

So that's sort of the Ryan budget, you know, major, major reduction in the size and scope of the government and a downsizing of the American welfare state, where the government would have much less role in protecting Americans from sort of the vagaries of misfortune. That's - I think that's a pretty fair way to describe it.

GROSS: Now, you think that if Romney wins the presidency, that the person to understand is actually Congressman Ryan. Romney said that he supports the Ryan budget. He said I think it would be marvelous if the Senate were to pick it up and adopt it and pass it along to the president. Why do you think if Romney wins that Ryan's really the person to watch?

LIZZA: I think that Romney has been very reluctant in this campaign to lay out a specific policy agenda, and I think there's a strategic reason for that. The Romney campaign believes that if they win, it will mostly be because the public has soured on President Obama, and Romney is sort of your, you know, your only alternative so that the campaign really is a referendum on the president so that Romney shouldn't be out there offering too many details because when you offer details, you just get attacked.

Now into that vacuum has come this agenda that congressional Republicans have articulated over the last few years, and specifically the Ryan budget. And so just as Paul Ryan, who's been in Congress since 1998, just as - since about 2008, he has helped convince the entire Republican congressional caucus