Alex Salmond has been attacked by his rivals over his plan for leading the Scottish National Party from Westminster.
Mr Salmond defended his election plan
Mike Russell called the scheme "deeply flawed" while Roseanna Cunningham said the Scottish Parliament deserved more from the Nationalists.
The clash came on BBC Scotland's The Politics Show in the first debate between the leadership contenders.
Mr Salmond's surprise entry into the contest came last Thursday.
Sampling of party support shows that Mr Salmond, who led the party for 10 years up to 2000, has now snatched the mantle of favourite from Ms Cunningham.
The Scotland on Sunday newspaper said it contacted 67 of the SNP's 200 branch conveners, of whom 21 said they had not yet decided who to support.
But of the remaining 46, 39 voiced a preference for Mr Salmond.
The Sunday Times said that out of 46 party branches it contacted, 29 backed Mr Salmond and only five said their members would back Ms Cunningham.
The contest will be decided in a one-member-one-vote ballot of the party's 8,209 members and the result will be announced on 3 September.
Mr Salmond argues it makes sense for him to lead the party from Westminster while Nicola Sturgeon, his preferred choice of deputy, leads at Holyrood - particularly as the next electoral battle is expected to be a Westminster general election next year.
Mr Russell and Ms Cunningham now face their old leader
But Mr Russell said: "I think the policy that Alex has articulated on this is deeply flawed."
He questioned what would happen if Nicola Sturgeon did not win the deputy leadership.
"And the second problem is that I want to see more people in the Scottish Parliament becoming prominent," he said.
"The only reason why the party locks itself into first minister's questions is to show two alternative leaders of Scotland.
"If that's not the purpose of what is meant to be this great event, than I would like to see lots of other people participating, and calling the executive and (First Minister) Jack McConnell to account."
Ms Cunningham said Mr Salmond had changed his mind "on a great number of things".
"No matter how we look at this, the effective leader of the party will be in Westminster and I think the Scottish Parliament, particularly in the state that Scottish politics is in today, deserves far more from the national party than to have the next three years effectively being a contest not between the people who are bidding to be first minister," she said.
But Mr Salmond argued the situation was provided for in the SNP constitution, and the Salmond-Sturgeon "partnership approach" would be a strength, rather than a weakness.
He said: "The first elections that we fight are a Westminster election in nine months' time, and actually I want to lead from the front in that election.
"In 2007 I intend to run to be first minister of Scotland, because Scotland did not struggle and strive for self-government for 300 years to let it be run down by Jack McConnell and his gang of mediocrities."