OptionProbability
Market chaos
Bonus underlying chaos
Vacant Senate seats at start of term
Multiple Speaker ballots, or failure to elect a Speaker on the first day
Any state misses filing deadlines for certified results
Vacant House seats at start of term
Bonus market chaos
Senator not up for re-election changes party
Any major news organization retracts a call
New election ordered for any seat
Any member seated who was not the winner
Any member-elect denied the oath of office
Failure to establish a quorum in first roll-call vote (either chamber)
Any election delayed
Any member-elect changes parties
VP party change or otherwise announced change in Senate tie break
Congress refuses to accept any certified result
Majority control discrepancy in the Senate
Majority control discrepancy in the House
47
31
30
27
22
19
18
15
14
9
8
2