LINCOLN, Neb. (AP) — The Nebraska Republican Party is criticizing an Omaha senator who’s leading an investigation into the state’s prisons.

GOP Chairman J.L. Spray on Monday called for Sen. Steve Lathrop, a Democrat, to resign from the investigations committee.

Spray says Lathrop made “biased and prejudicial comments” last week while defending Democratic congressional candidate Brad Ashford from an attack by Republican incumbent Rep. Lee Terry, of Omaha.

Terry tried to connect Ashford with Nikko Jenkins, who killed four people in Omaha last year after his release from prison. Terry alleged that a committee Ashford leads failed to reform Nebraska’s “good time” law.

Lathrop blamed the Department of Correctional Services and noted that it’s run by Republican Gov. Dave Heineman.

The Nebraska Democratic Party says the state GOP is trying to silence the investigation.