Somerset County Freeholder Kenneth Scherer announced yesterday that he would not seek re-election to a fourth term, saying that he wants to spend more time expanding his landscaping and nursery business. Republicans had viewed the 47-year-old Scherer, a former Hillsborough Mayor, as a possible Assembly candidate when his political ally, Peter Biondi, retires. Two Hillsborough officials are considered possible candidates for the seat — Mayor Robert Wagner and Councilman Anthony Ferrara — but there is no guarantee that Somerset Republicans view Scherer’s seat as automatically going to Hillsborough. Three other Mayors have been mentioned — Patricia Walsh of Green Brook, Amey Mesko of Bedminster and Albert Ellis of Watchung – but several GOP sources say that those three lack the countywide appeal to win a Republican convention. Other possible candidates include Branchburg Township Committeeman James Leonard, the chief lobbyist for the New Jersey Chamber of Commerce, and Monthomery Councilman Mark Caliguire, the brother of Bergen County Executive candidate Todd Caliguire. Bridgewater Mayor Patricia Flannery would be a formidable candidate for higher office in the future, the insiders said, but that Somerse Republicans would not run her with Freeholder Rick Fontana, who is also from Bridgewater.