The Scotland striker is rumoured to be on his way back to Ibrox where he played for under Dick Advocaat in season 2000-01.
Miller, 28, failed to pin down a regular first team spot and after a spell at Wolves, he signed for Celtic in 2006 where he again lasted only one season before moving to Derby.
Edgar, spokesman for the Rangers Supporters Trust, insisted Miller's ability and not his time at Celtic was the sticking point among the majority of Ibrox supporters.
He said: "First of all, let me say that it's not for me to tell Walter Smith who to sign and if he does think that the best way forward is to sign Kenny Miller, then I will get behind him.
"Rangers fans in general would never tell any Rangers manager who to sign and certainly not Walter Smith.
"But the level of dissent shown by the supporters against a player who hasn't yet signed for us is unprecedented.
"I certainly haven't heard anything like it before.
"We were 2-0 up in a Scottish Cup final and the Rangers fans were singing against Miller that is an indication of how strongly the fans feel about it.
"He is a deeply unpopular player and it is clear that the fans don't want him and I would say it is the vast majority rather than a minority who feel this way.
"It has nothing to do with him being an ex-Celtic player, they don't like him because he is not good enough.
"Rangers fans don't care about a player's background and they would have no problem with signing an ex-Celtic player if he was going to improve the team.
"But Miller has had two attempts at the Old Firm, both at the time when the clubs were champions, and he failed spectacularly.
"He played in a Celtic team that won the title by around 20 points and he scored four goals.
"So will Rangers fans welcome him with open arms? No."