Rep. Paul Ryan (R-Wis.) is about to become the most important Republican, and maybe the most important politician, in America. Tomorrow he unveils a budget plan that will cut at least $4 trillion from the deficit over the next 10 years, put forth a pro-growth tax reform plan, convert Medicaid to a system of block grants, and redesign (and thereby save) Medicare. He made a splash on Fox News Sunday, rekindling hopes of a presidential run.

Ryan laid out his approach on the show:

CHRIS WALLACE: So more than $4 trillion, which is a significant number, because that was the president’s debt commission cut the deficit by $4 trillion.

RYAN: Yes, we will be exceeding the goals that were put out in the president’s debt commission.

WALLACE: How do you do that?

RYAN: By cutting spending, reforming entitlements and growing our economy. Look, we intend to not only cut discretionary spending and put caps on spending, you have to address the drivers of our debt. We need to engage with the American people on a fact-based budget, on stopping politicians from making empty promises to people and talk to the country about what is necessary to fix these problems.

Now the good thing we have going for us is we have time to fix this problem. So the kinds of reform we’re going to be putting out there won’t make changes to people who are already in or near retirement. If you’re 55 or older, you won’t see changes. You won’t have to reorient your lives around these things.

But if we keep kicking the can down the road and keep making more empty promises to people, then we’ll have the European kind of pain and austerity. Then you have cuts to current seniors, tax increases that slow down your economy.

By addressing the drivers of the debt now, we do it in a gradual way. We can guarantee the mission of health and retirement security, not just for current generations, but for future generations. And we are going to put out a plan that gets our debt on downward trajectory and gets us to a point of giving our next generation a debt-free nation. That in and of itself will help us grow the economy today and create jobs.

He is not Pollyanish about the fight ahead:

WALLACE: Last question, as you look ahead, and a lot of people would say look, the answer is you’re not going to get this budget passed. It’s really setting up an issue and — and a sensible debate for 2012.

As you look ahead to the next election, aren’t Democrats going to be able to say, look at Paul Ryan, look at the House Republicans. They want to kill Medicare, they want to kill Medicaid, they want to gut the programs that you depend on. Aren’t you playing into the Democrats’ hands?

RYAN: We are. We are giving them a political weapon to go against us, but they will have to lie and demagogue to make that a political weapon.

Look, we don’t change benefits for anybody over the age of 55. We save Medicare, save Medicaid. We save these entitlement programs. We repair our social safety net, and we get our country a debt-free country for our children and grandchildren’s generation. And we get jobs. We get economic growth.

They are going to demagogue us, and — and it’s that demagoguery that has always prevented political leaders in the past from actually trying to fix the problem. We can’t keep kicking this can down the road.

The president has punted. We’re not going to follow suit. And, yes, we will be giving our political adversaries things to use against us in the next election, and shame on them if they do that.

The left will scream (despite earlier criticism that Paul Ryan’s plan wouldn’t do enough), but the real danger may come from the right. Ryan’s Medicare plan is not touching benefits for those 55 years and older. (There is a good argument, as New Jersey Gov. Chris Christie (R) has made, that you can’t spare current beneficiaries if you want a timely solution to our fiscal woes.) If Ryan did address current beneficiaries, the savings would be far more dramatic. The conservative Republican Study Committee will come out with its own plan that will be more dramatic than Ryan’s. It may be that Ryan is savaged by both sides, and his plan collapses. But, if we look on the positive side, the more extreme plan may draw the fire, hammering home the point that Ryan’s approach isn’t radical at all. In fact, it’s the bare minimum we should be doing if we are to head off a debt crisis and get the country’s finances on sound footing.