The 2024 election includes any special election that may be held concurrently, as well as the outcome of any subsequent runoff to decide the winner of a House or Senate seat.
A member's party affiliation shall be determined by the ballot-listed party affiliation of the individual elected to that seat. An individual elected who does not have a ballot-listed affiliation with either of the Democratic or Republican parties will nonetheless be considered to be affiliated with one party or the other in the event that, as of 12:01 a.m. (ET) on Election Day, such person a) is an incumbent who is a member of that party’s caucus; or b) is not an incumbent but who has most recently publicly stated the intention to caucus with that party.
Should the Democratic and Republican parties control an equal number of Senate seats, control of the chamber shall be determined by the party affiliation of the Vice President-Elect at the time that the Senators are sworn in.
Determination of the winners of Senate and House seats shall be based on state election authority certification or other final official determination of the general election results for each state after all challenges are resolved.
I will trade in this market, but I think the resolution criteria are pretty well defined (taken from an old predictit market). I will resolve the market according to these criteria.