Looking from Europe, US politics often seems bizarrely right-wing. Part of that is an artefact of the electoral system.
Voter turnout is small, and heavily biased towards the relatively better-off sections of the population. That skews electoral politics.
In the run-up to the November 2012 polls, according to the French journal Convergences Révolutionnaires:
• Sixteen states have restricted the ability to register on the electoral roll on the day of voting. Experience shows that this possibility has sometimes increased the participation by 10 to 12%, especially among young people and new voters ... likely to vote for the Democrats. In addition, the states have put new obstacles in the way of associations that help voters to register by collecting registration forms.
• At least nine states have sought to suppress voting before official polling day. The goal is to eliminate the vote on the Sunday before the Tuesday election day. Many black communities have a tradition of voting after Sunday services. More than 30% of the votes in the presidential election of 2008 took place before polling day.
• Thirty-four states now require new identity checks. It is not easy to obtain official identity documents. It requires a birth certificate. Many elderly and poor people do not have a birth certificate, because they were born at home, or have lost it. Many people without cars have no driver's licence, the most common form of identification. Students who study in another state do not have the local identity card, etc. In all, between 7 and 15% of voters do not have proper identity documents and will struggle to get one in time with the job cuts in the offices responsible for issuing them.
On top of that, vast numbers of workers in the USA are "illegal" immigrants, and not on voter rolls for that reason.