President Obama has stared the need for entitlement reform in the face — and immediately blinked.

For a brief moment it appeared that Obama was willing to take on one of his party’s most prized shibboleths: the idea that there is nothing wrong with Social Security and Medicare that repealing the Bush tax cuts won’t fix. But faced with a rebellion by House Speaker Nancy Pelosi and the net-roots left, it is clear the president now plans to put off any serious effort to reform those programs.

But facts are stubborn things. The combined unfunded liabilities of Social Security and Medicare top $100 trillion. Indeed, without reform, Social Security will begin running a deficit within eight years, by 2017. And Medicare faces a deficit even sooner. If current trends continue, Medicare and social Security, along with Medicaid, will consume 28 percent of GDP by mid-century.

Obama has the opportunity to show that he truly represents a change from Washington politics as usual. If he retreats from obvious challenges so easily, he will fail.