Johnson said Anne Arundel County has suffered from "a tremendous lack of leadership" for several years and he can use his experience to elevate the county's reputation.
Johnson highlights his many years in law enforcement and in county and state government. He said he's built relationships over the years that he can leverage to benefit county residents.
"You're going to get somebody who knows the county at every part that exists. I know what people want in north county is far different from what people want in south county," he said.
On the Republican side, there are two announced candidates who are drawing a lot of attention: County Executive Laura Neuman, who was appointed last year to replace Leopold, and Del. Steve Schuh, who has had his eye on the top job for several years.
Primary elections will be held June 24, with early voting from June 12 through June 19.