IF REPUBLICANS are serious about governing responsibly, they have an odd way of showing it. And for politicians who purport to hate the deficit -- odder still. The House Republicans' "Pledge to America," unveiled with fanfare Thursday at a Sterling hardware store, mixes irresponsible tax cuts with implausible spending caps and unspecified actions to control entitlement spending. The resulting concoction is a profile in cowardice.

"Our debt is now on track to exceed the size of our economy in the next two years," their document notes. "The lack of a credible plan to pay this debt back causes anxiety among consumers and uncertainty for investors and employers."

Good points. Sadly, the "Pledge" contains no credible plan to reduce this debt. On the contrary, it would increase the debt by $4 trillion -- yes, trillion -- by extending all the expiring Bush tax cuts and adding new ones, including a poorly conceived deduction for small businesses. Talk about picking winners and losers; the tax code is already laden with special benefits for small business. This latest deduction would cost $25 billion over two years.

The Republican plan promises dramatic spending cuts. It would roll back non-security discretionary spending to 2008 levels and cap future growth. But it shirks the politically sensitive task of explaining where the savings would come from. It tosses out a few, relatively small-dollar ideas -- "cutting Congress' budget" and "imposing a net hiring freeze on non-security federal employees," saving $35 billion over 10 years -- and then resorts to the old waste, fraud and abuse dodge. Minority Leader John Boehner crowed that the rollback would save $100 billion in the first year alone. Yes, but from where? Anyone can make that promise; tell us which NASA programs you will end, which national parks you will close. The proposal would require cuts of more than 20 percent in discretionary funding, the deepest in recent history. Leave aside the upside-down claim that cutting spending by this amount in the midst of an economic downturn would help create jobs. What, exactly, do Republicans propose to cut?

The biggest dodge of all involves entitlement spending. The Republicans would repeal the Obama health-care plan, a plan that at least holds out the prospect of slowing the growth of health-care spending in general and Medicare in particular. An earlier proposal by Rep. Paul D. Ryan (R-Wis.) at least had the honesty to outline major, if unwise, changes in Medicare; he would turn it into a voucher program. By contrast, the "Pledge" vows grandly to "make the decisions that are necessary to protect our entitlement programs for today's seniors and future generations. That means requiring a full accounting of Social Security, Medicare, and Medicaid, setting benchmarks for these programs and reviewing them regularly, and preventing the expansion of unfunded liabilities." Asked about this big fat asterisk, Mr. Boehner promised "an adult conversation." When? What was this, the children's hour?

Democrats haven't been any clearer about dealing with entitlement spending -- the party's hands-off Social Security caucus is growing ever louder -- and their position on extending tax cuts looks good only in comparison to Republicans' greater irresponsibility. But if this is the Republican case for taking control, the national debt can rest easy.