Democratic U.S. Senate candidate John Bohlinger says he will also use his campaign to lead an effort to change the Montana Constitution.

Bohlinger says civil rights are threatened by warrantless invasions by the federal National Security Agency.

He said Tuesday he wants to expand constitutional restrictions on warrantless searches to cover digital communications. He says it would send a message to federal agencies.

It takes nearly 50,000 signatures from registered voters to change the Constitution. Bohlinger says he will lead the signature-gathering effort as he runs against Lt. Gov. John Walsh in the Democratic primary.

Bohlinger previously served as a Republican lieutenant governor and state senator.