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.
Analysis from the Manifold newsletter:
Nevada: Sen. Jacky Rosen (D) vs. Sam Brown (R)
Democrat win chances per models: 81% (The Hill), 90% (538), 85% (Split Ticket)
Expert forecasts: Lean D (Cook), Lean D (Sabato), Tilt D (Inside Elections)
Polling average (538): Rosen+8
Election result in 2018, a Democratic wave year: D+5 (Rosen vs. Heller)
Election result in 2012, amid Obama's reelection: R+1.2 (Heller vs. Berkley)
Recent Nevada presidential election results: Biden+2.4 (2020), Clinton+2.4 (2016), Obama+7 (2012)
Manifolder commentary:
Plasma Ballin’: D+7 according to GOP internal polls
Conflux commentary:
On the 538 podcast I mentioned earlier, skepticism was expressed that Jacky Rosen would really win by 8 points in a state as much of a tossup as Nevada — which voted for the winner in every presidential election between 1912 and 2012, was trending blue in 2016, but seems to be going a little redder in 2024. But she leads by 8.
Sam Brown, who served in the military, “sustained burns to thirty percent of his body due to an improvised explosive device injury in 2008.” He supports abortion, although according to The Guardian, “Rosen has categorized [him] as extreme,” while Jacky Rosen — who defeated an incumbent Republican in 2018 — is “a pragmatic, old-school bipartisan focused on local issues.” Ultimately, Rosen is leading in the polls and therefore the forecasts.