Even some Harvard Econ professors understand why the Obama/Sestak stimulus plan failed:

The Administration should have endorsed a stimulus package
based on a repeal of the corporate income tax and reductions in
employment taxes. This policy would have accomplished its
stated goals, and the budgetary implications would have been
less negative than those of the package ultimately adopted be‐
cause this alternative plan would have enhanced rather than de‐
tracted from economic efficiency. This approach would also
have been difficult for Republicans to oppose.

Yet the Administration did not take this approach, presuma‐
bly because its true goals were not just economic stimulus. In‐
stead, the Administration wanted to reward its constituencies
(unions, environmentalists, public education) and increase the
size and scope of government. This tactic is consistent with the
Administration’s policies in general. Across the board, it has
taken a big government, redistributionist approach, whether re‐
garding housing, unions, health, the auto industry, trade, anti‐
trust, or financial regulation. The Administration’s view appears
to be that government is better than individuals at deciding how
taxpayers get to spend their money and that government should
engineer large transfers from richer to poorer.

Pat Toomey couldn't have said it any better himself.