So, it seems all the more surprising that the federal government still has $100 billion to $150 billion in stimulus money left to spend. That’s about as much as the Making Work Pay tax credit that gave $800 apiece to middle-class families in 2009 and 2010. And it’s twice as much as Congress gave to states to stabilize budgets and save education jobs…

Taking back money from slow-moving infrastructure projects like high-speed rail and spending it on sooner-starting projects or on short-term stimuli like food stamps is easier said than done and might create more problems than it fixes, according to economists and current and former White House budget officials.

“It’s meaningful, but it’s not a game-changer,” said Mark Zandi, an economist at Moody’s Analytics who has followed the stimulus. “From an economic and political perspective, I’m not sure that would make a lot of sense to do. A lot of this spending has generated a lot of planning, a lot of environmental designs. They’re counting on the money. If you’re going to divert it, you’re going to create all kinds of problems for them.”