Most policymakers in Washington agree the economy needs help. One problem: The subject dominating the economic policy debate right now — the Bush tax cuts — ranks low among temporary measures that might offer the best bang for the buck. And making the tax cuts permanent without paying for them would be expensive and could constrain the country’s economic growth prospects in the medium- and long-term. Those are two key points that Douglas Elmendorf, director of the Congressional Budget Office, offered to the Senate Budget Committee on Tuesday.