IMO the 250 senators are key to electing the Prime Minister but not necessarily a done deal for Prayut. The 250-person Senate is composed of 194 members selected by the ruling junta and as of 2020, only 104 of the 250 senators are military or police officers. 50 senators were from professional and social groups and not appointed by the ruling junta. All members served 5 years up till 2024. If UTN and PPRP don't do well in the election as most have predicted and unable to form the government, the senators will likely to be looking beyond their service to ensure the best outcome for their future.Those who may harbour thoughts of being re-elected for another of 5 years (senators are very well paid up to 100k+ monthly) may abandon their support for Prayut. After all, senators like all other politicians can be infuenced by better offers and political pressure.