Not Holy, nor Roman, nor an Empire, but just maybe Europe's best defense again an Empire of Blood
The unified states of Germany. Once on the verge of collapse, the rise of Vampiric Britain has breathed new life into the Empire.
Each state in the Empire has one vote. One elector. Each state contributes to the Empire's standing army, under the command of Holy Roman Emperor. Each elector can put forward motions to the Holy Roman Senate. In times of peace, majority wins.
In times of war? The Emperor himself holds dictatorial power. After all, it worked for Rome, right?