The example always used is its own refutation. kuchinich was confronted with the fact that if it had been his vote that killed health reform, his own voters would have abandoned him. On the other hand the WH has little credible threat to use against conservative senators. Nelson's funders and voters don't care what a black liberal in the WH says. And in spite of that the WH ran over nelson when it had the votes.

A lot of American "progressives" have a weird idea that things are supposed to be fair instead of being determined by power.

Of course, Greenwald is a right wing hack in disguise so his argument is probably not even sincere.

http://rootedcosmopolitan.wordpress.com/2011/04/20/glenn-greenwald-neither-a-liberal-nor-a-progressi ve/