Possible Clues:

• Clergyman about to turn, who may make one cross
• One in favour of Eatanswill's Slumkey wore a blue cockade
• Leader chooser
• Politician's target
• One to be initially verified on the electoral roll
• Campaign to increase Election Day participation
• One exercising a franchise
• Make overt change, as supporter of politician
• One looking for a ticket, maybe
• Polling booth user