The Robins have yet to add to their squad during the close season despite being linked to a host of names but Johnson is hopeful that something could be imminent.
He told the club's official website: "We're still in the race with the players.
"Our supporters understand why we don't mention any names, but rest assured we are working very hard behind the scenes.
"It's very close now. We'll keep things under our hat and reveal things when it's the right time."