Gurley, who played for the Atlanta Falcons last season, was in Detroit last week to visit with the organization.
"Look, we have interest in Todd. We do, and we're talking with he and his agent. ... We have interest in him," Campbell said during Thursday's OTAs. "But I would say this: Just because we have interest in him, that does not affect our feeling and our thoughts on both [D'Andre] Swift and Jamaal [Williams]. It does not.
"I think if we could do it sooner than later we would like to, but look, we're not gonna set a deadline on it," he added. "We do, we have interest in the guy, but that's kind of where it is right now."
On the day of Gurley's meeting in Detroit, Swift said he would welcome that knowledge and experience with open arms.
"I'd be happy if he comes here as well," Swift said last week. "I just want to compete with these guys. Just to have him in the building, that'd be good."
Gurley, 26, is a three-time Pro Bowler who has twice been the NFL rushing touchdowns leader in addition to being named the 2017 NFL Offensive Player of the Year. While many are expecting Swift to be the starter as a second-year running back, the Lions' coaching staff is interested in making the organization better. The Lions are also looking at the leadership of Gurley and Williams to help the room.
"Aw man, Todd Gurley, I mean the name. You sit back and you say his name and all kind of highlights just pop up," Lions running backs coach Duce Staley said Thursday. "Here's a guy who has been very successful in the league. Here's a guy, you go back a couple years ago, was unstoppable, and we're looking at anybody that can help the Lions and Todd Gurley definitely can help the Lions."