In the weeks before Election Day, millions of voters will hear from callers with surprisingly detailed knowledge of their lives. These callers — friends of friends or long-lost work colleagues — will identify themselves as volunteers for the campaigns or independent political groups.

The callers will be guided by scripts and call lists compiled by people — or computers — with access to details like whether voters may have visited pornography Web sites, have homes in foreclosure, are more prone to drink Michelob Ultra than Corona or have gay friends or enjoy expensive vacations…

After these conversations, when those targeted voters open their mailboxes or check their Facebook profiles, they may find that someone has divulged specifics about how frequently they and their neighbors have voted in the past. Calling out people for not voting, what experts term “public shaming,” can prod someone to cast a ballot…

In interviews, however, consultants to both campaigns said they had bought demographic data from companies that study details like voters’ shopping histories, gambling tendencies, interest in get-rich-quick schemes, dating preferences and financial problems. The campaigns themselves, according to campaign employees, have examined voters’ online exchanges and social networks to see what they care about and whom they know. They have also authorized tests to see if, say, a phone call from a distant cousin or a new friend would be more likely to prompt the urge to cast a ballot.