With regards to infrastructure spending we should sear into our minds the old saying "haste makes waste." I think it would be much better for Obama to deliver a smaller fiscal stimulus in the current year but plan infrastructure expenditures in the out years. Liberals may decry that postponing spending is a waste of recession. However, I fear that this criticism will ultimately be undermined by a prolonged recession, thus giving rise to plenty of opportunities for clamoring for more spending. In the meantime, it would be better to wait for some of the worthier projects to become "shovel-ready" than plow ahead and repave all of West Texas in search of the vaunted fiscal multiplier.
update: I retract what I said about Krugman. Here is an op-ed where he also advocates spending over the next several years.