What accounts for the sudden decline in the fortunes of America’s labor unions? Wasn’t it just a few weeks ago that labor leaders helped elect the most liberal chief executive in modern times? Even before he’s sworn in, the debates over the automaker bailout and Card Check are making clear that as important as the White House is, you can’t succeed if your policy goals are so unpopular that they have a hard time passing Congress.

We’ve seen how unpopular the UAW bailout is, and blackhedd today explains that the bailout debate may well dominate Barack Obama’s first 100 days. The unions may ultimately get the bailout they’re aiming for, but if they do it’s likely to require tens of thousands of job losses, and it may require Obama to spend a lot of political capital.

It seems that the effort to pass Card Check is running into similar trouble. Specifically, most Democrats seem to recognize that it’s not very popular, and they’re running from a difficult vote. Last week, Arkansas Senator Blanche Lincoln aired her doubts about Card Check. With a re-election campaign coming up in 2010, she seems uneasy about the prospect of defending a vote to eliminate the secret ballot for union organizing. But if Lincoln’s concern is her re-election bid in 2010, what explains the similar unease about Card Check from her home-state colleague Mark Pryor — who coasted to re-election unchallenged just 6 weeks ago?

[Pryor] attempted to alleviate concerns that the bill would be on the fast track that union leaders had hoped for in the new Congress. He predicted that a President Obama wouldn’t push the measure in the first six months of his administration and that he might wait until 2010 to bring it up.

“That bill has really never had the chance to go through committee, be amended and have floor debate … in the Senate,” he cautioned. As a result of that process, he predicted that the bill would change in committee hearings and that any Senate bill would look much different than the House bill.

It’s not just Arkansas Democrats who are sending the message that Democratic Senators are worried about Card Check. It’s Harry Reid, too. He and the Senate Democratic leadership seem very unenthusiastic about a vote on Card Check any time soon. Some Democrats have suggested that Card Check should wait until next year.

But Card Check will never get any more popular than it is now. If Democrats push through a Big 3 bailout on a large scale, voters will be even more concerned about a second major bill that looks like a payoff to Big Labor. Additionally, there’s the simple fact that relatively few Americans have heard of Card Check; as more are educated on it, opposition is likely to build. Add in the fact that Obama and Senate Democrats are bound to lose some popularity simply from running Washington in a time of recession, and it’s not hard to see that deferring Card Check to 2010 may mean avoiding a vote indefinitely. For that reason, labor leaders can be counted on to put on a full-court press to vote early — probably soon after new Senators are seated in Colorado, New York, Delaware, and Illinois.

And while it seems today that Democrats are eagerly backing away, don’t underestimate the amount of pressure that will be put on by the unions. Harry Reid, Nancy Pelosi, and Barack Obama are keenly aware that their majorities depend on the donations and legwork of the labor unions; they will do everything possible to make sure the unions remain healthy. It seems likely to set up a bruising battle that will do a lot of damage to Democrats, no matter how it plays out.