Synonyms for Canvasser (same or very similar meaning)
WordNet sense 1 (a petitioner who solicits contributions or trade or votes):
solicitorWordNet sense 2 (someone who examines votes at an election):
scrutineerWordNet sense 3 (someone who conducts surveys of public opinion):
pollster, headcounter, poll takerFrom the ODE community, based on WordNetadd/edit