Had Mr. Romney been the least bit serious about assembling a real tax plan, he would have known this. Instead, he hurriedly threw together his 20 percent tax-cut plan a week before the Arizona and Michigan primaries in February, at a time when Rick Santorum was proposing a similar idea. He said he wouldn’t touch middle-class tax breaks, and would “work with Congress“ to find offsets to the cuts.

“Work with Congress.” Would that be the same body that almost caused a government default last year? Given how dysfunctional Congress has become, the real question is what policies a president will demand of Congress, and how forcefully he will fight for them. Telling voters that Congress will decide which tax breaks to eliminate is saying that you don’t have the courage to make a choice.

On issue after issue, the dominant theme of Mr. Romney’s plan is a refusal to make real choices. He talks endlessly about his 59-point plan “to get America back to work,” but you can scrutinize all 160 pages of his economic booklet without finding any evidence of decision-making. A few examples:

He says he wants to cut nondefense spending by 5 percent, and cap federal spending at 20 percent of the economy, down from about 24 percent. But what would that actually mean in terms of programs cut and services reduced? The plan is silent. The programs he mentions cutting are the comically minuscule national endowments for the arts and the humanities, foreign aid, family planning, Amtrak and a few others — all tattered Republican punching bags.

The plans Mr. Ryan submitted as House budget chairman — which are now Mr. Romney’s too — were never models of clarity, but they at least made his priorities quite stark: more than three-fifths of his cuts would come from low-income programs like job training, Pell grants and food stamps. That’s not something Mr. Romney ever talked about on the stump, raising the question of whether the vice-presidential choice will end up defining the man at the top of the ticket better than Mr. Romney has himself.

Mr. Romney wants to offload federal responsibility for Medicaid and move it entirely to the states by turning it into a much cheaper block-grant program. He claims this approach would save $200 billion a year, but never mentions that this would force states to drop coverage for at least 14 million people when states are unable to keep up with rising medical costs, which would raise emergency costs at local hospitals. He says he supports Mr. Ryan’s plan to provide the elderly with a fixed amount to buy either traditional Medicare or private plans, but has also said he would issue his own Medicare plan this fall, far too late.

Beyond his standard line about undoing financial reform and Mr. Obama’s “anti-carbon” agenda, Mr. Romney has also vowed to repeal any Obama regulation that might burden the economy, without telling us which ones. Could he mean the power-plant rule that keeps mercury out of children’s lungs, perhaps? Or the one requiring better brakes on big trucks? Or the one expanding disability protections to people with AIDS or autism? Don’t expect an answer.

The Romney campaign decided long ago that it didn’t need a real economic plan of its own when it could just bash the president’s. “As long as I continue to speak about the economy, I’m going to win,” he said last month. Voters, he is saying, need not inquire further.