“Schumer’s basically doing what McCain tried in the election,” says Mark Krikorian, executive director of the Center for Immigration Studies. “[That is] to agree that ‘enforcement first’ is the right approach, but to argue that the enforcement has already happened and now it’s time to proceed to amnesty.” Schumer’s proposal is filled with features that sound tough but likely won’t be at all tough in practice. Krikorian warns that Schumer’s promise to employ high-tech enforcement techniques in the future might come at the cost of amnesty today. After the amnesty is in place, the enforcement measures might never get done.

And it’s not just that. Is this time of great economic distress really the right time to argue for greater immigration? “You want to bring more people in?” asks one incredulous GOP aide on Capitol Hill. “That was a hard case to make when unemployment was four percent, much less when it’s almost ten percent.”

And then there’s time. Even if Democrats make room in the Senate schedule to address immigration — a big question, given the fights over cap-and-trade, health care, Sonia Sotomayor and other issues — there’s real doubt about whether another big bill can be done amid the rush. That’s why Schumer gave himself a little wiggle room by saying the bill would be passed “this Congress,” meaning anytime between now and the end of next year. Finally, there’s the opposition. A few years ago, Senate Republicans were evenly divided on the Kennedy-McCain immigration measure, a bill that had the strong support of a Republican president. Now, it’s likely the opposition will be more unified.