A former Aboriginal Affairs and Northern Development Minister says Stephen Harper's choice for a new minister will say a lot about his priorities.

John Duncan resigned as Aboriginal Affairs and Northern Development Minister last Friday after admitting he shouldn't have written a character reference to the tax court. Duncan was in the position for about two and a half years.

Robert Nault, who was minister of the then-Department of Indian Affairs and Northern Development from 1993 to 2004, said federal ministers don't stay in the Aboriginal Affairs and Northern Development portfolio for long because it's hard to make a political mark in that position.

Nault's term as minister was one of the longest in that position since former Liberal PM Jean Chretien served there in the 1970s. Nault now runs his own consulting firm, working mostly with First Nations.

He said the Aboriginal Affairs and Northern Development minister is often stuck dealing with outdated legislation, making it difficult to create any change.

"So, you just bide your time and then you try to convince the prime minister to move you," said Nault.

"Most people spend a short period of time there. They don't have a lot of experience relating to aboriginal issues. They don't have a lot of history around working in that particular area, so they go somewhere where they feel a lot more comfortable."

Nault said Canadians don't generally have a feel for aboriginal issues and so it's hard to appeal to a majority of Canadians on the issues.

Nault said if Prime Minister Harper doesn't give the next minister a clear mandate then very little is likely to be accomplished.