In the all-important Halloween-costume poll, it’s shaping up to be President Obama in a landslide, according to iParty Corp., a Dedham-based chain of party-goods stores that counts Halloween as its most important sales season.

In many years, popular movies --- and pop culture, in general --- can greatly influence costume choices for trick-or-treaters, said iParty chief executive Sal Perisano. Spider-man has had a Halloween heyday, and Batman too. But given the proximity of Election Day to Oct. 31, recent presidential campaigns often play a role when adults think about which celebrity they want to impersonate on Halloween.