Blue Dog Democrats have introduced an amendment to balance the federal budget by 2020. How that might happen, they don’t say. To get an idea just how tough that would be, look at Republican U.S.Representative Paul Ryan’s Roadmap for America’s Future. It gets the budget in balance without raising taxes by huge entitlement spending cuts. In 2020, his plan would produce deficits of close to 4 percent of GDP — and rising. His first balanced budget doesn’t arrive until 2063.