Over the past year, Republicans have learned something important about negotiating budget deals with Democrats: If you don’t like their offer, just wait a couple of months.

Capitol Hill Democrats, constantly ceding ground. (Susan Walsh/Associated Press)

Today, many Democrats would love to go back in time and accept the McCaskill-Sessions bill. And the same thing may well happen in the deficit “supercommittee.”

Consider the evolution of the debt deals over the past year. There was the Bowles-Simpson proposal, which raised taxes by $2 trillion and cut the deficit by more than $4 trillion. Democrats, in general, were cool to the plan. The White House never embraced it. Liberals nicknamed it “the Catfood Commission.” Republicans were also reserved in their embrace, but that, in retrospect, looks prescient.

The next major budget plan that emerged was House Budget Committee Chairman Paul Ryan’s. It was a nonstarter with Democrats — perhaps even a political boon for them — but it dragged the conversation to the right. Then came President Obama’s budget plan, which looked quite a lot like Bowles-Simpson, but reduced the defense cuts by $600 billion and lowered the tax increase by $500 billion. In other words, the Democrats moved to the right of Bowles-Simpson.

Then came the debt-ceiling debate. By the end of those negotiations, Obama had offered Boehner a deal that would cut the deficit by about $4 trillion, with only $800 billion to $1.2 trillion coming from revenue. That deal would also have raised the Medicare eligibility age to 67, cut Social Security and made the Bush tax cuts permanent. It was far to the right of both Obama’s previous offer and the Bowles-Simpson commission.

Last week, some of the Democrats on the supercommittee offered the Republicans a plan that would include about $1 trillion in revenue. That put it near even with the president’s proposal to Boehner. The expectation this week is that they will offer the Republicans yet a bit more than that, putting them well to the right of the president’s offer to Boehner, which was in turn well to the right of the president’s previous proposal, which was in turn well to the right of Bowles-Simpson.

So far, Republicans have not said yes to any of the deals the Democrats have offered. They continue to assume a better deal is just around the corner, and thus far, they have been right. Currently, they may be assuming that yet a better deal could be struck with, say, President Mitt Romney, and if he wins the election, they may well be right. If Obama wins, a reinvigorated Democratic majority might prove them wrong. But the fact remains: Their strategy of saying no has, thus far, paid great dividends, though not ones Republicans have decided to collect.