How one views whether a person is politically "left" or "right" is determined by ones own political position. From the point of view say, of of an extreme-right evangelical, a more moderate conservative like say, John McCain, is criticised as being on the "left". It's a matter of perspective.
The Political Compass folks have put together a U.S. Presidential Primary version and came up with rather interesting results.
Keep in mind when looking at this...
"...that The Political Compass is a universal tool, reflecting the full spectrum of political thought, and applicable to all democracies. US politics are generally fought within a more confined space. While in mainstream America, Clinton, for example, may be seen as left leaning, in the overall political landscape, she is a moderate conservative. Someone like Kucinich, while seen by his severest opponents as an extreme left winger, would qualify as a typical social democrat in a European context."
What this helps to illustrate, that many have realised for quite sometime, is that the American political system, is in practice, more conservative than other Western democracies. While the Democrats might very well be to the "left" of the Republicans on political issues, they are "conservative" when compared to the Western political parties as a whole. Consequently, United States political candidates, at least those that get elected, tend to be more conservative. The only real question is in American politics is, how much. There might be a radical party, but it's not the Democrats.
In reality, there is no practical "radical left" or even a "left" in the two party system in the United States. There effectively is only moderate conservative and more far-right conservative factions. The "left", regardless of the far-right's attempt to frame and label their moderately conservative opponents as fringe and "far-left", simply doesn't exist as a significant political party. It may have an influence on the political system, but not through it's own candidates and platforms and only participates vicariously in the political system though support of the least conservative of the two parties.
Also interesting, is that libertarianism isn't represented either. Nearly all the candidates fall in the authoritarian side of the spectrum, and the Republican candidates even more so. Even Ron Paul, often described as a Libertarian candidate, still falls on the Authoritarian side of the line from a global perspective. Only two candidates fall on the libertarian side of the grid, both Democrats. Power corrupts? Because those in power are in positions of authority do they tend to be more authoritarian?
Which leads me to another observation. That American Libertarianism has been hijacked by the right, mostly over the issue of taxes. Perhaps that's why I often find myself on the south-side of many libertarians. I'm typically more libertarian than American Libertarians. So is DailyKos really made up of a bunch of "extreme leftists" as the media and the far-right portrays, or is it DailyKos that represents the political "moderates" in a political arena full of conservatives?
What this also shows is the United States political system is remarkably authoritarian for a country that prides itself on it's individual liberty and freedoms. It also illustrates that too many in our political system, are far too eager to sell out those freedoms for security and power.