"Mitt Romney will put critical health care for women and families at risk and will let politicians interfere in your most private, personal medical decisions," the ad says. "President Obama trusts women and knows the health care challenges families face."
Pandora, with 58 million active monthly users, has emerged as a popular advertising destination. Users of the site are required to furnish their ZIP codes when registering, giving campaigns ample data for ad targeting.
Sean Duggan, vice president of advertising for Pandora, said that candidates used to advertise on Pandora primarily to reach younger voters but that the age range has rapidly expanded this year. He said both Republicans and Democrats were advertising equally on the channel and they were rapidly buying up inventory.
Associated Press writers Nedra Pickler in Washington, Philip Elliott in Cleveland and Brian Bakst in Green Bay, Wis., contributed to this report.
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