Last week, as federal regulators seized Washington Mutual in the largest U.S. banking failure, Congress was grappling with whether to spend $700 billion of public money to fix the financial industry's troubles.

Lawmakers' initial reaction to the Treasury Department's staggering request: shock. That sum amounts to about a quarter of the U.S. government's annual spending. It's more than the Pentagon's annual budget, more than the nation pays out each year in Social Security benefits and more than the federal government's cost...