He has been linked with West Brom and has trained with Arsenal to keep up his fitness, but Campbell is looking at which clubs are showing firm interest.
And the 35-year-old believes joining Newcastle could allow him to play a part in a promotion campaign before returning to the Premier League, where he has previously played for Tottenham, Arsenal and Portsmouth.
Campbell told ESPN Soccernet: "I have been approached by several clubs, and yes, it is correct to say that Newcastle are one of them.
"People might be surprised to hear me say that I would be very interested in a move there, but I have my reasons. Also, Newcastle are a big club and could be heading back to the Premier League. It appeals."
Sheff. Utd v Newcastle. Click here to bet.