Taibbi's recent Obama rant must be cathartic for some liberals upset with Obama, but the article is misguided. The kicker gives the gist:
What's most troubling is that we don't know if Obama has changed, or if the influence of Wall Street is simply a fundamental and ineradicable element of our electoral system. What we do know is that Barack Obama pulled a bait-and-switch on us. If it were any other politician, we wouldn't be surprised. Maybe it's our fault, for thinking he was different.
Yglesias partially understands the problem with this view:
The implicit theory of political change here, that pivotal members of congress undermine reform proposals because of “the White House’s refusal to push for real reform” is just wrong. That’s not how things work. The fact of the matter is that Matt Taibbi is more liberal than I am, and I am more liberal than Larry Summers is, but Larry Summers is more liberal than Ben Nelson is. Replacing Summers with me, or with Taibbi, doesn’t change the fact that the only bills that pass the Senate are the bills that Ben Nelson votes for.
There are a few ways to change the votes of politicians: 1) kick them out of their jobs and hope for more progressive or conservative candidates, which isn't very easy to do and might backfire 2) sweeten the pot most likely by cramming a bill full of pork carefully tailored to interests in the politician's district or state 3) make the bill align with the politician's principles.
Numbers two and three are often used in tandem with substantive changes to a bill serving as political cover to let a politician vote for the pork. The Lieberman analysis this morning focused on Lieberman's character and his desire to settle old grudges. That's part of it, but he is also protecting major contributors to his office. Ben Nelson might get a bigger percentage of donations from the health care industry than Lieberman, but Lieberman doesn't have the Democratic Senatorial Campaign Committee's money to rely on or worry about. Nelson is less likely to openly flaunt his differences with the party because he can't afford to offend the DNC to the same degree Lieberman can.