But I think there's another powerful incentive that she and other similarly situated Democrats face: the desire to maintain their own power, through being at or near the crucial fulcrum (now apparently 60 votes!) on which bills teeter between passage and the bottomless pit of endless debate.

In that light, it seems to me hardly an accident or a surprise that Democratic Senators (and Joe Lieberman) situated at spots 55-59 in the current majority would tend to oppose any changes to the running of the Senate that would increase the importance of 50/51-vote thresholds and decrease the importance of 60-vote thresholds. As long as the 60-vote line is the big, important line, people like Lincoln, Landrieu and Nelson, along with Lieberman, Snowe and Collins, run the Senate. They are the key power players. If the Senate abolished today's absurd cloture/filibuster system and moved instead to a 50/51-vote threshold, a different (and slightly more diffuse) cast of characters would become the key power players: those Senators who are around the 51st-most-likely to support a controversial Democratic bill. Maybe Tim Johnson, Claire McCaskill, Mark Begich, etc. Had the health care bill been passed under these different rules, we would have a Senate bill that, instead of buying off Nebraska with extra federal funds, instead contained some hidden giveaway for Citigroup (Tim Johnson) or maybe a special provision for rural clinics in Alaska. It matters a lot who's at the fulcrum of power.

This creates a powerful and important obstacle to reform. Even if mainstream Democrats begin to push hard in our public discourse for changes in Senate rules, Democrats who might not be needed for a 51-vote majority but ARE needed badly for a 60-vote cloture motion face a different set of incentives. Specifically, they have incentives to shoot down proposed changes that would limit their power (thereby providing "bipartisan" cover for opposing any such changes). In a way, all this suggests to me that if you want to make the Senate a more majoritarian institution, it might, perversely, be easier to make this happen if you had a slimmer Democratic majority-- maybe only 52 or 53 seats. Under those conditions, Lincoln, Landrieu, Nelson, and Lieberman would be at the fulcrum of a majority vote, while the 60-vote threshold would make the fulcrum the seventh, eighth, or ninth most moderate Republicans. Then perhaps Blanche Lincoln et al. could be persuaded that the cloture/filibuster system is an antidemocratic Frankenstein's monster that needs to die.