Thoughts from Kansas had a good point awhile ago regarding the benefits of having a push from the left in American politics. In the late 19th and the first half of the 20th century, there was a serious progressive voting presence in the United States which acted to pressure the two major parties leading them (the Democrats and Republicans) to soften their stand on unions, labor laws, voting rights and other progressive issues.
From 1904 through the 1924 presidential election, Socialist candidates were able to get at least 2.78% of the vote. The high was in 1912 with 6% of the vote going to Eugene Debs. The election was unique in that Teddy Roosevelt ran under the Progressive banner splitting the Republican vote allowing Woodrow Wilson to win. Many concessions were made to the progressives/socialists as the two major parties were trying to woe these progressive voters. The 16th Amendment established the right for Congress to enact income taxes, the 17th established the direct election of Senators and with the 19th women across the country gained the right to vote.
In 1924, the Progressive/Socialist coalition candidate, Robert LaFollette from WI, drew almost 17% of the vote and even got 13 electoral college votes. Many of their proposals in some form or another got folded into the New Deal. As FDR's New Deal expanded, the vote of the socialist candidates went down. In 1932 the Socialist candidate drew 2.2% of the vote by 1944 they were getting only 0.16% of the vote (WWII also playing a role).
In 1948 concerns about a Post-War economic slowdown and the Cold War gave rise to many 3rd parties. The Socialists drew only 0.28% of the vote. The Progressives drew about 2.38% of the vote though. This was countered though by the rise of the States' Rights (pro-segeragation) candidacy of Strom Thurmond who drew about 2.41% of the vote. In 1968, Wallace under the American Independent banner (once again pro-segeragation) received about 13.6% of the vote. The "States' Rights" movement drew from the Southern Democrats and was a reactionary response to the Civil Rights movement playing on the fears many white Protestants in the South had regarding Blacks and the left.
The Republicans, under Nixon, undertook the Southern Strategy to get those "Dixiecrats" to vote Republican, a tradition that stands to this day (hence the continued visits of Republicans to Bob Jones' University).
Until Nader (and that is debatable), there haven't been any strong 3rd party progressive candidates for president. A note, Nader in 2000 got 2.7% of the vote. Anderson and Perot were right of center candidates which encouraged the two parties to become even more similar to one another. Many liberals derided Nader and blamed him for Gore loosing to Bush in Florida. Never mind the reality that significant numbers of registered Democrats did not vote in the 2000 election in Florida and the logic makes a big assumption that all the Nader votes would have gone to Gore. Kerry in 2004 ran as a "centrist" and lost not just the electoral count but also the popular vote. Bush (as previous Republicans had been trying to do) expanded the Southern Strategy to Middle America, playing once again on the fears of white suburban/rural Christians.
Progressives in this country can not just go along with the Democratic Party (especially when they put a pro-war candidate up for president against the Republican pro-war president, when a good chunk of the nation was against the war). They must push for a strong third party candidate of their own. Force both parties to take notice. Change the nature of the debate. The politics of Bush is a direct result of the rightward push from the States' Rights movement of Thurmond's and Wallace's runs for the White House. Fears were played to and not confronted. What have many progressives done? Cower around the Democrats and agree to compromise. The problem is that is not something you compromise on, it is something you fight.
Has voting for Democrats in Congress stopped the War in Iraq? Has it ended the assults upon our civil liberties? Nope. Way to go.
What is fun is pointing this out to the fine folks over at the DailyKos.Tends to get the inmates a little rilied up.
(Presidential Election Info)