The United States Congress is the deciding source, and the deciding value is the number of Democratic Party members listed for the US Senate in the current-members listings on Congress.gov on the first business day after January 3 of the year following the 2026 election, or after the convening date set by law if that differs. Seats held by independents and vacant seats do not count toward any party. The outcome is Yes if that seat count is at least the value specified in the market question and No otherwise. The outcome can be decided early, before official certification, if the Associated Press, The New York Times and The Wall Street Journal have each called every House and Senate race for the same candidate and no recount, legal challenge or other official proceeding that could affect the result is pending or announced; otherwise it stays open until those conditions are met or the results are officially certified, with resolution scheduled for 7:00 AM CT when Congress.gov publishes the member list after the new Congress convenes. If that member list is delayed, resolution waits until it is published.

The United States Congress is the deciding source, and the deciding value is the number of Democratic Party members listed for the US Senate in the current-members listings on Congress.gov on the first business day after January 3 of the year following the 2026 election, or after the convening date set by law if that differs. Seats held by independents and vacant seats do not count toward any party. The outcome is Yes if that seat count is at least the value specified in the market question and No otherwise. The outcome can be decided early, before official certification, if the Associated Press, The New York Times and The Wall Street Journal have each called every House and Senate race for the same candidate and no recount, legal challenge or other official proceeding that could affect the result is pending or announced; otherwise it stays open until those conditions are met or the results are officially certified, with resolution scheduled for 7:00 AM CT when Congress.gov publishes the member list after the new Congress convenes. If that member list is delayed, resolution waits until it is published.