The Shooters, Fishers and Farmers stalwart Robert Brown has been knifed as the party's lead candidate for the NSW upper house just weeks from the state election.

Mr Brown, who has served in the Legislative Council since 2006 and is the party's longest-serving member, was replaced by Mark Banasiak, the chairman of the Shooters, Fishers and Farmers.

Shooters, Fishers, Farmers Party MLC Robert Brown was knifed as the party's lead candidate for the upper house on Tuesday. Credit:Jon Reid

Mr Brown said he was blindsided by the move, likening it to a "coward's punch".

"I didn't see it coming. And I didn't get up off the floor after I was hit," Mr Brown said.