Is this disagreement warranted?
Let's use the following over-simplified graphic to describe politics in America.
Simplified Landscape of US Politics in 2009
Let's call groups like PDA the "Strict Progressives", and let's call groups like DFA and MoveOn the "Centrist Progressives". (Another pair of names for these two groups is "Further Left" and "Near Left". If anyone has better ideas for names, please let me know. I considered using the pair of names "Progressive Left" and "Moderate Left", but what does "moderate" mean? Everyone considers their own position to be moderate. Choosing names is perhaps harder and more significant than we think.) The graphic is simplified and incomplete in many ways; for example, libertarians are generally anti-war, though, like other conservatives, they generally oppose government programs.
Of course, the health care industry, with the support of Republicans and conservative Democrats, are fighting tooth and nail against any sort of public option that would threaten their immense profits.
Strict Progressives will admit that it will be difficult to get agreement in Congress on single-payer, but they insist that if progressives compromise too soon and too easily, we'll be left with something very unsatisfactory. When you're trying to sell a house, you start by asking for a high price and then you compromise as needed. Agreeing from the start to give up on single-payer is really dumb. We must insist on what's best for America: single-payer. Anything less will perpetruate our current sicko system.
More generally, the issue is this: Strict Progressives regard MoveOn and DFA as "compromisers" who are too willing to work within the corrupt Democratic Party. (I have friends in the anti-war movement who would never associate with the Democratic Party.) Howard Dean, who heads DFA, was Chair of the Democratic National Committee from 2005 to 2009, and MoveOn threw its weight behind numerous Democratic candidates. Disagreement between the Strict Progressives and the Centrist Progressives extends beyond the issue of health care reform. For example, last year many MoveOn members were upset that MoveOn.org didn't come out in favor of impeachment. I myself left MoveOn last year, because of its too centrist stances, because of its top-down remoteness, and because it asked for money too often (like every day).
There is also plenty of disappointment about Obama and the Democrats' embrace of Bush-era policies such as militarism and bank bailouts. But I think one of the biggest disappointments is that Obama is "looking forward" rather than trying to hold the Bush Administration accountable for its crimes.
Of course, PDA prides itself on working both within the Democratic Party (with people like Dennis Kucinich), and outside the Democratic party. But PDA definitely holds to a stricter standard of progressive values than groups like DFA and MoveOn.
What's even more ironic is that the vast majority of Democrats at the grassroots level (I've heard 85%), and almost certainly nearly all members of MoveOn and DFA, want single payer health care! Centrist Progressives think, however, that single-payer is not "feasible" right now, so instead they support a "strong public option" that will be a stepping stone towards eventual adoption of single-payer. If the public option is strong enough -- if it's not riddled with booby traps and shackles -- it will eventually lead to single-payer.
Thing is: everyone knows that anything that Congress comes up with is likely to be riddled with compromises and handouts and pork. But, one hopes that on this core Democratic issue, President Obama and the Democrats will show at least some leadership and principle. We must hold them accountable. (Think Iran.) When will Obama use his political capital?