These ratings represent our attempt to forecast the outcomes of this November’s elections, using the best information we have available. As circumstances warrant, we’ll issue changes in these ratings from time to time. To keep up with any changes, please subscribe to our free newsletter, the Daily Kos Elections Morning Digest, which we send out each weekday. And for a comprehensive overview of how our ratings work, please check out our detailed methodology statement.

In brief, here’s how we define each of our ratings categories:

Tossup: Both (or all) parties have a strong, though not necessarily perfectly equal, chance of winning. Lean Democrat or Lean Republican: One party has an identifiable advantage, but an upset victory is possible for the other party. Likely Democrat or Likely Republican: One party has a strong advantage and is likely to win, though the race has the potential to become more competitive and an upset cannot be ruled out. Safe Democrat or Safe Republican: Barring unforeseeable developments, one party is certain to win.

Note that even within each category, not all races are equally competitive: One race in the Lean Republican grouping, for instance, might be on the border of being a Tossup, while another could be closer to Likely Republican. In addition, in most election years, Tossup races in aggregate tend to favor one party over the other rather than split evenly between the two.