I think Ezra Klein nails this:
As Dan says, we’ve not yet seen Obama’s negotiating style come into focus. But we will soon. That said, I don’t know how many times a president has to fail to solve this problem before we admit that it’s not a matter of presidential messaging, or toughness, or will, or strategy. FDR, Truman, Nixon, Carter and Clinton all took runs at this prize. All of them failed. And Lyndon Johnson went for Medicare and Medicaid because he was daunted by the challenge of comprehensive health-care reform.
That’s right. I know a lot of people on the left who seem to have voted for Barack Obama because they liked his progressive agenda, then gotten excited when Obama won the election because they liked his progressive agenda, then Obama proposed progressive measures to the congress and they were excited, then it turned out that key congressional players like Collin Peterson and Rick Boucher and Max Baucus were less left-wing than Obama so actually legislative outcomes would be considerably less left-wing than Obama’s campaign proposal. It’s all well and good to be disappointed with this situation but it doesn’t make a ton of sense to me to do what a lot of people seem to be doing and becoming disappointed with Obama.
I recall back during the primary campaign that there was a kind of misguided sentiment out there that the key factor influencing whether or not we could get comprehensive health reform or good energy legislation in 2009 was whether you believed Obama’s story about “bringing people together” or John Edwards’ story about “fighting” or Hillary Clinton’s story about gritty experience and determination. The fact of the matter, though, is that legislating is about who controls the veto points. The difference between a conservative president whose ideas are checked by the 40th most liberal senator (Mark Warner or Mark Begich, it seems) and a progressive president whose ideas are checked by the 60th most liberal senator (Ben Nelson or Olympia Snowe) is pretty enormous. But when comparing two different possible progressive presidents, the fact remains that the veto points are going to be where they’re going to be. On foreign policy and some other matters the president has tons of discretion and it’s a different story. But big-picture domestic legislation in the modern era is controlled by congress.