Liberals have a problem in that they both criticize deficit spending by Republicans while at the same time supporting measures that do even worse damage to the deficit. They love to bring up the Clinton years when he and a Republican congress (they don't mention the latter) got to a balanced budget. But where is the Clinton starter-kit out there? There aren't any Democratic centrists left, it's possible that Hillary would have used the same playbook her husband did when she found out Keynesian economics doesn't work but we'll never know.
And so liberals have no answer to deficits except to try to outgrow them and raise taxes at the same time. This is a real problem as growth and tax increases don't exactly go hand in hand. But liberals believe you can tax more, regulate more and the increased government spending will lead to growth and jobs and prosperity. And the public in 2008 gave the Democrats the keys to give 'spending' a try. Didn't work. But the liberals can't give it up.
I think deficits will be the undoing of liberal power for years to come as deficits will only get worse and worse. It is hard to argue for more spending when there's so many examples of it failing in the first 2.5 years of the Obama administration.
How will they adjust? I would argue their only strategy is tearing down the Republicans as soulless evildoers, bought by special interests trying to exploit poor people to preserve tax cuts for the rich. I think though common sense will hold out as people understand that you can't have prosperity with exploding deficits. I think the Republicans are winning the argument at the moment. If they can stay on message I think liberalism is in trouble for the foreseeable future.