Back in 1972, my Dad, a crusty old New Deal Democrat, pointed out to me the futility of George McGovern's nomination, even as he cursed out Nixon and gladly voted for McGovern.
"The Democrats aren't supposed to nominate liberals," he fulminated, "they're supposed to nominate centrists who depend on the liberals, so the centrists can enact liberal stuff but not take all the heat."
He also pointed out the the role of the left in the Americna context was to agitate for things that appear radical now, but, once the public gets used to the idea, will get adopted with a minimum of controversy.
In other words, Henry Wallace had no business running for president, it was a hopless and quixotic task that just made things harder for Truman, who ended up winning and keeping the New Deal on track. (For those of you who dont get the references, see below the fold)
[Wallace and Truman were 1940's Democratic presidential contenders. Wallace was Vice President 1941-45, a progressive type, who got dumped for Truman, who might be considered more "DLC" . When FDR died in '45, it was Truman who ended up in the White house. Wallace ran in '48 on a minor party ticket that cost Truman electroal votes from a number of blue states. Actually, there was a 4th party, too. Strom Thurmond, who ran on an anti-civil-rights platform, and cost the Dems a number of southern states.]
http://hnn.us/articles/1173.html
America is basically not a particulalry progressive society. The latest poll figures indicate that 30% of the population are wingnuts, 20% are "moonbats" (that's us) and 50% are "moderates," whatever that means. I suspect it means that while they are repulsed by some of the worst excesses of the wingnuts, the stuff the moonbats throw out scares them more. This is probably because the moonbat stuff -- feminism, deep ecology, gay marriage, socialism, etc. -- is not as familiar to them as the wingnut stuff. It's the "devil you know vs. the devil you don't know. And, don't forget, middle of the road America believes in ideals that sound more like wingnut rhetoric than moonbat rhetoric. Sorry, that's just our history. In fact, it's amazing that our political system has been able to incorporate any progressive ideals at all.
The result of the distribution of political attitudes is that it's easier for the wingnuts to take political power than it is for the moonbats. After all, they only have to get 21% of the moderates on their side, we have to get 31%. That wasn't always the case -- I suspect that during my youth, when the Dems had a seemingly permanent lock on power, and even when Republicans were elected, they acted like Dems (look at Nixon's domestic policies -- he founded EPA for one thing).
The Job of the left, therefore, is not to get involved in electoral contests and enforce ideological purity on the Democratic party. That's the path to permamnet wingnut rule. The task of the left is to be out working (even in Red state wingnut territory) to change American attitudes so that public opinion is distributed in a more congenial manner -- say, 30% moonbat, 60 percent "moderate," and 20% wingnut. In such a world, having Joe Lieberman as senator wouldn't be so bad.
Remember, it's not so much which party is in control, it's what policies they enact, and if they think doing something will lead to defeat at the polls, they won't do it, whatever their idelogocal position.
Today, the left works from a position of weakness. They need to change hearts and minds if they expect to influence elections any more than they do now (which isn't much.)