Possible Clues:

• One with a vote
• One high in Roman Empire finally overcame Hannibal
• Start of evensong with minor churchman and constituent
• Constituent of power on the Hill?
• Certain voter
• ''College'' member supporting a president
• German prince raised duty, squeezing City traders at first
• One with the power to cross a prince
• One makes one cross from time to time
• One who makes one cross at times