It’s interesting to note how precisely the vote to end debate on the economic stimulus legislation corresponds to the gridlock zone model of the political scientist Keith Krehbiel. In the current configuration of power, the model predicts that the 59th most liberal senator — the so-called filibuster pivot — determines the fate of any legislation that would move the status quo in a liberal direction. As such, Obama should move policy as far to the left until the filibuster pivot is just barely willing to accept it.

That appears to be exactly what happened. Remember, Democrats have 58 seats pending a final outcome in the Minnesota race and they needed 60 votes. If we use Keith Poole’s 110th Senate rank ordering of estimated ideal points and assume new Democrats are to the left of Evan Bayh (the most conservative Democrat) and new Republicans are to the right of Olympia Snowe, Susan Collins, and Arlen Specter (the most liberal Republicans in that order), then we find that the pivotal senator is Collins with Snowe to her left and Specter to her right. The final vote corresponds almost precisely to the prediction — Obama compromised with Snowe, Collins, and Specter and they were the three Republicans who joined 58 Democrats in voting in support of cloture.

The media has berated Obama for failing to attract sufficient Republican support, but the reality is that he didn’t need more than a handful of GOP votes in the Senate (nor did he need any in the House). Should he compromise away what he thinks is good policy just to appease Washington insiders? That would be, as he said, “bipartisanship for bipartisanship’s sake” — at best a second-order goal and one that can’t take priority over policy in a crisis of this magnitude.