Because he allowed the democrats to reverse welfare reform

Pres. Barack Obama vowed to correct the mistakes of the Bush administration but instead is determined to undo one of the great successes of the Clinton years: welfare reform. Democrats have inserted provisions into the catch-all stimulus bill that will reverse Clinton-era welfare reform, re-establishing the wasteful, incentive-killing system whose transformation was the bipartisan pride of the 1990s.

Prior to reform, the federal government simply gave the states more money for every family they added to the welfare rolls. The predictable result was that the states worked hard to maximize their welfare caseloads in order to maximize the amount of federal funding they could therefore claim. The system had zero incentive to help people make the transition from welfare to work and independence—in fact, the states were financially punished for doing so. The Clinton-Gingrich reforms replaced that bounty-hunter system with a flat rate for each state, based on population and other factors. That gave state-level welfare authorities a better set of incentives, encouraging them to use their resources in the most effective manner and to reserve them for the truly needy.

http://article.nationalreview.com/