Sensenbrenner "may be the most legitimate voice on the issues" because of his work on the Patriot Act, said Mark Jaycox, a policy analyst with the Electronic Frontier Foundation.
Sensenbrenner sent a letter to Attorney General Eric Holder last month asking him whether the Justice Department believes Section 215 authorizes carte blanche collection of Americans' phone records and other personal data. He followed up with an additional letter this week and said he has yet to receive a response.
"We're going to have a vigorous debate, whether they like it or not," Sensenbrenner said.
Jaycox added that recent revelations over the past month have bolstered the position of lawmakers who want to address oversight of domestic surveillance.