1) HubrisOr a bit of all of them. After all, "pride cometh before the fall". And, either their fall will come in the form of political suicide and severe repercussions in the November elections, or it will be a calculated suicide, justified as martyrdom to a cause greater than the will of the American people whom they represent.
Their bullheadedness about sticking to the existing bill for health care reform, along with other blatant expressions of hypocrisy, power grabbing, and partisan displays have surpassed the patience of even some of the formerly faithful to Obama's agenda.
Briefly, some recent examples just from today...
1) Pushing forward with reconciliationOne explanation, along the lines of martyrdom is that they realize they're in for trouble in November, so they might as well go for broke and get as much of their original desires for health care reform passed.
2) Pushing for it, despite the parliamentarian's warning, and deciding that Biden, and not the parliamentarian gets to ultimately decide if reconciliation is appropriate.
3) Recent video showing Biden specifically chide Republicans for trying to take a power grab and saying in a morally superior way, something to the effect of "I hope that when the Democrats are in power, we wouldn't make such a blatant expression of power grabbing as the Republicans are doing today."
4) And unrelated to health care, but consistent with the hypocrisy displayed at every turn, Pelosi is letting Rangel's ethical misconduct slide when "Pelosi was among the loudest calling for resignations and prosecutions, and effectively used the scandals in her “culture of corruption” campaign in 2006."
5) And, in another split personality moment, Pelosi just aligned herself and her party with "some of the views of the Tea Partiers in terms of the role special interests play in Washington D.C."