Saying he favored retaining the Resident Trooper program as the primary police agency in Carroll, First Lt. Kenneth L. Tregoning announced yesterday he will run for sheriff. "My professional background has prepared me to confidently seek the office of sheriff for Carroll County," Lieutenant Tregoning said in a prepared release. The 25-year police veteran said he favors keeping the Resident Trooper program as long as the Maryland State Police provides that service. The county currently pays the state to provide troopers for the county's primary police agency. "I am not a proponent of a county police force," said Lieutenant Tregoning, the commander of the state police barracks at Golden Ring in eastern Baltimore County. "I was a member of two study committees looking into the feasibility of a county police force and each one recommended, first, to keep the Resident Trooper program, second, to look into a county police force and third, to expand the sheriff's department to assume those duties. I concur with those recommendations." Lieutenant Tregoning said strong internal policy could have helped prevent the morale and legal problems that resulted from the firing of two deputies by Sheriff John H. Brown. One of the men was ordered rehired in a court decision. The candidate said he was a Democrat most of his life but became an Independent about 15 years ago because he was not pleased with the candidates then. He returned to the Democratic party in September.