Liberal Democrats hate the spending cap. As the population ages, it would force future Congresses to transform Medicare. Conservative Republicans hate the deficit cap. It would force big tax increases in years ahead to go along with big spending cuts…

Once there is a serious spending reduction on the table, that changes the whole psychology. There are many Republicans who, in those circumstances, would support a tax reform package that didn’t raise tax rates but that did, when scored dynamically, raise a lot of tax revenue. That would make Democrats happy.

The whole thing could be enforced by adopting a version of the Bipartisan Policy Center’s save-as-you-go idea. This is like the pay-as-you-go rules that restrained spending and debt in the 1990s, only it is much tougher. If Corker’s spending caps and Reid’s deficit caps got together, the save-as-you-go plan would be their love child.