Rangers manager Walter Smith is keen on the forward who he knows well from his time in charge of the national team.
The Derby striker has already played for both sides of the Old Firm and would be available for £2.2million if Derby are relegated.
"There weren't too many problems when I signed for Celtic. Even though I was an ex-Rangers player the fact I signed a pre-contract gave everyone five months to get used to the idea. I played for Rangers' greatest rivals and didn't get a lot of stick from the fans. There might have been the odd comment but society has moved on. Most people wouldn't have a problem."
The 28-year-old admitted he does not fancy dropping down a division at the end of the season.
"Championship football is the last thing I'd want at this stage of my career. I'll speak about my future with the Derby manager at the end of the season. A lot of players will come and go."