Huffington Post reported last week on a testy exchange between House Budget Committee Chairman Paul Ryan and Sen. Rand Paul while Ryan was briefing Senate Republicans on his 2012 budget proposal, which has already passed the House. Rand Paul has proposed a budget that balances within five years while Ryan’s takes years to reach principal balance.

Sen. Paul said Rep. Ryan’s plan did not do enough to cut spending and relied on too much deficit spending for too long, according to the aides.

Ryan gave it right back to him. The budget committee chairman went directly after Sen. Paul’s five-year budget plan, which he had clearly studied closely. Ryan’s criticism went roughly like this: yes, he said, you slash the Department of Education and make fast, dramatic cuts, but you don’t deal with entitlement spending. In the out years the deficit would sky-rocket, he said, making an air chart with his hand moving through the air and pointing sharply upward.

The story goes on to note that Paul is planning separate proposals for dealing with entitlements, and has already teamed with Republican Sens. Mike Lee of Utah and Lindsey Graham of South Carolina on Social Security reform — the one entitlement untouched by the Ryan budget. As my column today makes clear, I’m sympathetic to the broad outlines of what Ryan is trying to do and obviously I’m in agreement with Ross Douthat here:

The goal for conservatives, ultimately, has to be a sustainable right-of-center entitlement reform. If the Ryan budget is understood as a first step toward such a reform – a bold initial statement that establishes the G.O.P.’s seriousness on the deficit, provides a rough draft for later legislative efforts, and sets the stage for fruitful discussion and debate – then it will have served its purpose. If it’s treated as scripture that can’t be compromised or altered, then we’re all going to be in a lot of trouble.

Nevertheless, I do think there is something to Rand Paul’s critique. In addition to a blueprint going forward, Republicans need to contemplate what they can do right now. As I said in this earlier post, there are pitfalls to relying too heavily on the fiscal responsibility of future majorites, and not just Democratic ones. Significant parts of the Gingrich Congress’ legacy, for example, were undone by future Republican Congresses.