Hunch. Osborn runs a second time with the Democratic party behind him and no Democrat on the ballot, after losing by 6.7 points in 2024.
The 2024 gap market resolves on the same results: YES if Ricketts leads Osborn by less than 6.7 points of all votes cast, or if Osborn wins, and NO if the lead is 6.7 points or more. The 6.7 is Deb Fischer's lead over Osborn in 2024 in the official US results, and the certification on 30 November settles it if the count is not final on 4 November.
We looked for cases where a sitting US senator faced a candidate with no party, and the other big party had no candidate on the ballot. We found six such races from 1990 to 2024 in the official results. The senator was a Republican each time, and John Warner of Virginia won two of them. The 2024 race was Osborn’s first try.