Here is a page from the NYTimes which shows the races in the US Senate for 2012. According to it, the Dems have 41 and the Republicans, 44 safe seats. It then gives information on the races that will be hard fought in the next year. Furthermore there are tabs at the top for the caucus/primary schedule for president in 2012 as well as a page for comparing the fundraising of the presidential candidates. An exercises that might be useful for your classes would be to compare fundraising and polls and ask which occurs first "the chicken or the egg?" In Cain's case, polls led to increased money raising and in Romney, it is probably the other way around.