Nelson is aware that the Democratic "centrists" killed Clinton's effort at health care reform in 1993. He thinks that history is predictive. He'd better be wrong.
If Nelson and the centrists can kill health care reform, then the Democratic Party is as doomed as the conservative Republicans have already proven themselves to be. That means that both major parties will go into the November 2010 election after being completely out of touch with the voters and quite discredited. With both current major parties self-discredited by the 2010 election then what comes out of November 2010 is simply unknowable. But the public is going to latch onto something. This is the kind of event that revolutions are made of. In the extreme such a political event led to the 1917 takeover of what became the Soviet Union, and the 1933 Nazi takeover of Germany. But it is also what Franklin Delano Roosevelt headed off quite effectively during the 1930's.
It might be time right now to start building a true Progressive party outside the two major parties. The media won't figure this out for at least two election cycles. The conservatives, with their backwards view of politics as being a move to what was good in the past, cannot take advantage of such a situation. Progressives, however, are more capable of dealing with such s changing political and social situation.
This is, of course, pure "Blue Sky" thinking, but the problem seems to be that both parties are mired in the experience of the Congressional Leadership with the past, but facing a society and economy that is moving rapidly into the (currently undescribed) future.