The Obama administration, and the Democrats more broadly, have lost control of the narrative, and thus lost their power.
It is the media which generates alot of the external pressure to get things done, and once they're allowed to slow down and pick at the individual threads of a fraying effort (threads like Landrieu, Nelson, etc.) the problems only get worse.
If you'll remember the way the Bush administration worked, even with a slim majority, they would roll out a new initiative each week, and the ones that didn't work, they just let go of. Thus, they got large portions of their agenda through while not particularly suffering for the things that failed. (even the major ones like social security reform.)
Now, I'm not saying that I would model the Bush policies, and alot of the blame does fall on Congressional Democrats (four months to reach an "in principle" Senate healthcare deal?,) but I think the key lesson of the first year is that the Obama folks allowed the narrative to flag, effectively ceding agenda setting and offense/defense to the tea party/Republican rabble, to the media, to the Congressional Democrats, and to anyone else who wanted to scream loudly enough to gain attention for their own purposes.
The 24 hour news networks seek to fill their vast programming spaces, and if you don't provide enough fodder, they will look elsewhere, and you will lose control of the agenda setting narrative.
So, something new every full week Monday. Pick the argument for the week, and you largely win the argument for the week. Build a sense of momentum where everyone looks to you for the topic of the week. Sure, you're not going to get everything you want, but you'll get alot, and then, when those results lead to more popularity, momentum, and power, then you can turn the screws.
PS. "Moral" appeals like "we were sent here to serve the people," or trying to guilt Republicans into "bipartisanship" will never work. It is power and leverage which get things done.