When it comes to advancing a jobs agenda, the White House seemed to be doing nearly everything right. President Obama delivered a very effective speech to a joint session of Congress; the DNC got involved with a coordinated message; and the president hit the road and was well received in key battleground states. Polls show the American Jobs Act is off to a fairly strong start and congressional Republicans have not yet formed an opposition strategy.

So what’s the problem? Near the top of the list, apparently, is congressional Democrats.

President Obama anticipated Republican resistance to his jobs program, but he is now meeting increasing pushback from his own party. Many Congressional Democrats, smarting from the fallout over the 2009 stimulus bill, say there is little chance they will be able to support the bill as a single entity, citing an array of elements they cannot abide.

Some Democratic lawmakers think the bill is too big; some think it’s too small. Some don’t like the financing; some don’t like the spending. Some are afraid of the word “stimulus,” and some are upset the plan includes tax cuts.

I don’t want to overstate the intensity of the Democratic hand-wringing. At a certain level, this is just what Democrats do whenever any idea is put on the table — they start complaining. This has happened before, even under this president, as something akin to a throat-clearing exercise. Democratic lawmakers responded quite well to Obama’s speech last week, and it’d be a mistake to assume Dems “oppose” the Americans Jobs Act.

That said, there are three things congressional Democrats should keep in mind.

First, party unity matters. Obama is tackling the single most important issue on the minds of the American mainstream, and Republicans are feeling a little antsy. For Dems on the Hill to give the GOP cover by whining about an ambitious White House jobs bill, undermining the president on the issue voters care about most, is political suicide.

Second, Republican lawmakers hardly ever treat Republican presidents this way.

And third, whether congressional Dems realize this or not, their fate is tied to Obama’s fate. He remains the most popular elected official in Washington — by a wide margin — and the better he does, the better his party will do. The more Obama falters, the more congressional Democrats will suffer, too.

Especially after this week’s special elections in New York and Nevada, plenty of Dems are feeling nervous. That’s understandable. But undermining their own leader and helping defeat a popular jobs bill in the midst of a jobs crisis will not improve their odds of electoral survival.

As for the left in general, let this be the latest in a series of reminders — it’s easy to get frustrated with President Obama at times, but he’d be in a far better position if he had more reliable congressional allies to partner with.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.