If the Dawn Coalition believed the seat shouldn't have been taken up by Sofia Megame, then perhaps your candidates from the Pulian Imperial Party shouldn't have backed out when the Emperor requested one of the three non-elected Senatorial candidates to fill the vacancy.
Also, remember that no Senate can pass constitutional amendments alone. All constitutional matters passed in Senate go to a popular referendum according to the Pulian Constitution.
Also, remember that no Senate can pass constitutional amendments alone. All constitutional matters passed in Senate go to a popular referendum according to the Pulian Constitution.