Just as Republicans must learn to live with tax increases, Democrats must learn to live with — and vote for — changes in entitlements. They should keep in mind that reforms such as a chained consumer price index, which alters the inflation calculation applied to Social Security, and means testing the benefits of wealthy retirees, do not threaten the social safety net.

Neither Franklin Roosevelt on Social Security nor Lyndon Johnson on Medicare was wedded to any of the particulars of those programs — only the principle of guaranteed support from the government.

The road ahead is paved with compromises that many Democrats won’t like. The president will stick to his refusal to negotiate with Republicans who want to hold an increase in the debt ceiling hostage to spending cuts. But he will have to negotiate over the sequester — the $1.2 trillion in cuts to defense and domestic programs scheduled to take effect in two months…

If liberals are disappointed in Obama’s fiscal-cliff deal, imagine how they will feel in late February when he starts making tough choices on spending cuts. Liberals need to think harder about what their own long-term deficit reduction plan would be. Raising more revenue is necessary. It’s not sufficient.