Will eventually resolve to the party which won the popular vote for the race, as determined by the local, state, and ultimately federal governments.
In the case the race is called by the major news organizations, the market may optionally resolve early.
This market covers events up to and including Election Day, November 5: if Party A's candidate X wins the popular vote that day, but intervening events cause the next inaugurated Senator to be from Party B, the market will resolve to Party A.
If candidate X switches party affiliations, the switch will not affect the outcome if it is after the beginning of Election Day, local time.
1,000
3.00Analysis from the Manifold newsletter:
Washington: Sen. Maria Cantwell (D) vs. Raul Garcia (R)
Democrat win chances per models: 99% (The Hill), 98% (538), 99% (Split Ticket)
Expert forecasts: Solid D (Cook), Safe D (Sabato), Solid D (Inside Elections)
Polling average (538): Not enough polls
Election result in 2018, a Democratic wave year: D+17 (Cantwell vs. Hutchison)
Election result in 2012, amid Obama's reelection: D+21 (Cantwell vs. Baumgartner)
Recent Washington presidential election results: Biden+19 (2020), Clinton+16 (2016), Obama+15 (2012)
Commentary:
The polls were weirdly close in 2022, leading 538 to give an 8% chance of Republican victory, but this year there should be no drama.