Four conservative activists accused of trying to tamper with a senator's phones were just trying to record embarrassing undercover video of her staff ignoring phone calls from constituents angry that she supported health care reform, one of their attorneys said Thurday.

The four, including activist James O'Keefe, known for posing as a pimp and using a hidden camera to target the community-organizing group ACORN, were arrested Monday after targeting Democratic Sen. Mary Landrieu's office in a New Orleans federal building.