1. FiveThirtyEight

FiveThirtyEight says it aims to "cut through the clutter of this data-rich world", and it doesn't disappoint. Its beautifully clear maps and diagrams on politicians, polls, and predictions are accompanied by posts guiding you beyond the statistics to understand the underlying evidence. Essential reading.

2. Rasmussen Reports

Probably the most comprehensive coverage of US opinion polls, not only on the popularity of candidates, but citizens' views on almost anything. Crucial for understanding what the American public is thinking.

3. The Daily Beast's Election Oracle

The Election Oracle automatically gathers posts from across the internet and combines them with election poll data to build up what they claim are the most frequently updated predictions on the internet. Particularly interesting are the data on which candidates are winning the discussion on which issues across the internet.

4. The Huffington Post

America's leading liberal news website. Excellent insight into liberal American perspectives on the mid-terms.

5. Mark Mardell's America

Drawing on American culture and his own interviews, Mardell links the headlines and figures with human stories on the ground in the US. An interesting way to try to get inside the American psyche from a British perspective.