WASHINGTON – The most serious charge against Rep. Paul Ryan’s budget is not the risible claim, made most prominently by President Obama in his George Washington University address, that it would “sacrifice the America we believe in.” The serious charge is that the Ryan plan fails by its own standards: Because it only cuts spending without raising taxes, it accumulates trillions of debt and doesn’t balance the budget until the 2030s. If the debt is such a national emergency, they say, Ryan never really gets you there from here.

But the critics miss the point. You can’t get there from here without Ryan’s plan. It’s the essential element. Of course Ryan is not going to propose tax increases. You don’t need Republicans for that. That’s what Democrats do. The president’s speech was a prose poem to higher taxes – with every allusion to spending cuts guarded by a phalanx of impenetrable caveats.

Ryan reduces federal spending by $6 trillion over 10 years – from the current 24 percent of GDP to the historical post-World War II average of about 20 percent.

Now, the historical average for revenues over the last 40 years is between 18 percent and 19 percent of GDP. As we return to that level with the economic recovery (we’re now at about 15 percent), Ryan would still leave us with an annual deficit in 2021 of 1.6 percent of GDP.

The critics are right to focus on that gap. But it is bridgeable. And the mechanism for doing so is in plain sight: tax reform.

Real tax reform strips out exclusions, deductions, credits and the innumerable loopholes that have accumulated since the last tax reform of 1986. The Simpson-Bowles commission, for example, identifies $1.1 trillion of such revenue-robbers. In one scenario, it strips them all out and thus is able to lower rates for everyone to three brackets of 8 percent, 14 percent and 23 percent.

The commission does recommend that, on average, about $100 billion annually of that $1.1 trillion be kept by the Treasury (rather than going back to the taxpayer) to reduce the deficit. This is a slight deviation from revenue neutrality, but it still yields a major cut for the top rate from the current 35 percent to 23 percent. The overall result is so reasonable and multiply beneficial that it rightly gained the concurrence of even the impeccably conservative (commission member) Sen. Tom Coburn.

That’s the beauty of tax reform: It is both transparent and flexible. That flexibility and transparency can be applied to the Ryan plan. If you need a bit more deficit reduction to bridge the 1.6 percent GDP gap that remains after 10 years, you can get there by slightly raising the final rates.

Ryan’s tax reform envisions three brackets with a top rate of 25 percent. There’s nothing sacred about that number. In principle, you could raise all the rates slightly with the top rate going to, say, 28 percent – the top rate that came out of Ronald Reagan’s 1986 tax reform. You’re still much lower than the current 35 percent. And yet that final boost could bring you closer to a fully balanced federal budget at roughly 20 percent of GDP.

Nor would any great conservative principle be violated. The historical average of revenues – 18 percent to 19 percent of GDP – could be raised one point or so on the perfectly reasonable grounds that we are a slightly older society, and that we wish to avail ourselves of the extraordinary but expensive medical technology that can increase both the quality and length of life.

This one concession would yield a fully balanced budget more quickly than Ryan’s plan and would reduce the debt/GDP ratio even more steeply (because GDP would be growing, while debt would not). The effect on America’s financial standing in the world would be dramatic: Restored confidence in U.S. fiscal health would reduce interest rates, which would lower the overall debt burden, which could allow lower taxes, which could stimulate yet more economic growth. A virtuous circle.

That’s the finish line. But it starts with spending cuts. Serious cuts, as Ryan suggests – not the smoke and mirrors the Obama speech shamelessly presented as a plan.

Given the Democrats’ instinctive resort to granny-in-the-snow demagoguery, the Republicans are right not to budge on taxes until serious spending cuts are in place. At which point, the grand compromise awaits. And grand it would be. Saving the welfare state from insolvency is no small achievement.

© 2011, The Washington Post Writers Group