Karyn Hollis, an English professor at Villanova University outside Philadelphia, said the same computerized calls had been ringing her telephone as often as five times a day for more than a week.

They all start with a simple, if somewhat ambiguous, statement: "Hello, I'm calling with information about Lois Murphy," a Pennsylvania Democrat who is the challenger in one of the hottest House races. That opening sounds "kind of positive in tone," Ms. Hollis said. But the message quickly turns negative, blasting Ms. Murphy's political views. After she hangs up, the phone rings again later with the same message. And again. And again.