For a while now I’ve been keeping tabs on the tight races for U.S. Senate. Democrats need to gain six seats for control of the senate, and several states are too close to call, including Missouri, Virginia, Montana and now Maryland. To win control, Dems must win all of those races. (Note: Tennessee was a toss up, but it now looks out of reach.)
For a overview of where the senate races stand, check out the following sites, all of which average out the last several polls from multiple pollsters (Zogby, SurveyUSA, Rasmussen, etc.) for each race:
Pollster.com, run by a Democratic pollster, gives a U.S. map with each state color-coded to represent a Republican lead, a Democratic lead, or a toss up. A box above the map gives you the total numbers at a glance. Hover over a state and you get the average of the last five polls; click on the state to see the polls.
RealClearPolitics, a conservative site, is another option. This site has no map and includes only the most interesting races, but it lets you see the last several polls for each and their averages on one page.
National Review Online‘s Senate Boxscore is similar to RealClearPolitics, but the polls seem to be updated more quickly.
I recommend checking all three sites regularly, as the mix of polls is slightly different between each (for example, RealClearPolitics doesn’t include internal polls). Also, RCP and NRO both give a running prediction (often differing) of how many seats the Dems will pick up.