Unlike the Tea Party, most left wingers don’t really believe their own ideology. They put partisanship first, or they put the color of a candidate’s skin or the shape of their genitals over the candidate’s policy. Identity is more important to them than how many brown children that politician is killing.
So progressives have no power, because they have no principles: they cannot be expected to actually vote for the most progressive candidate, to successfully primary candidates, to care about policy first and identity second, to not take scraps from the table and sell out other progressive’s interests.
The Tea Party, say what you will about them, gets a great deal of obeisance from Republicans for one simple reason: they will primary you if they don’t like how you’ve been voting, and they’ll probably win that primary. They are feared. Progressives are not feared, because they do not believe enough in their ostensible principles to act on them in an effective fashion.
Things the Tea Party had that the "progressive blog movement" did not: An entirely approving 24-hour news network, plus a compliant network of "centrist" pundits all too willing to bow to pressure from that 24-hour news network to be less horribly liberal and consider "both sides" to issues like the fundamental humanity of women and morality of hideous torture and pre-emptive war.
Also a publishing network which made people who otherwise would be screaming on soapboxes into "bestselling authors" who then received fawning profiles in national "news" magazines. Magazines, too, which supported such leading lights of modern thought as Jonah Fucking Goldberg, and a syndicated columnist base consisting of such brilliance and fierce compassion as Kathleen Parker. All of this was set up during the Reagan and Clinton years, while Democrats were still cowering in fear of having their pictures taken with Jane Fonda.
All that existed before the first progressive blog ever lit up, and well before the Tea Party became a Bright New Light in American Politics. Their message gets reinforced every day, every hour, every minute, from a goddamn MEGAPHONE. It's overwhelming, especially to low-info voters, which is most voters, because in case you hadn't noticed this country is fucked and everybody's working hella hard just to stay in cereal and hand-me-downs.
And even more overwhelming than the conservative message is the apathy in the opposite direction, which is reinforced by every media outlet that is not overtly conservative: That none of this matters, that it's all too exhausting, that all politicians are horrible and destined to break your heart and why even fucking bother because boring, and here's something we can report that someone tweeted.
Look, I've noticed the blog audience cratering and my own efforts at publishing stories that should matter to progressives going nowhere, and I'm as pissed as anyone that I can't support a staff after nearly a decade of doing this, and that Ned Lamont isn't in Congress, and that John Kerry won't be Mr. President for the rest of his life, and that Howard Dean got fucked over, and that Obama isn't more liberal.
But I fault Obama voters and progressive "principles" in general much less than I fault the people who had the money to build a media empire of their own and focused it on vanity projects intead, or kept their powder dry so as to appease moral monsters at dinner parties. A failure of money and a failure to understand media infrastructure (miscasting the NYT as liberal and thinking that would be enough, for example) is not a failure to "believe your own ideology."