Sir Menzies Campbell insisted last night there could be no "sacred cows" for the Liberal Democrats as he came to the defence of his successor, Nick Clegg, in the party split over university tuition fees.
With the issue dividing the Lib Dem conference, the former leader insisted that "absolutely essential" services such as schools and hospitals would have to take priority in the queue for scarce resources.
Mr Clegg has infuriated senior colleagues with his insistence that the party's cherished commitment to abolish tuition fees might have to be downgraded to an aspiration.
Sir Menzies, speaking at a fringe meeting organised by The Independent, backed the controversial change of heart. But he also put himself at odds with another former leader, Charles Kennedy, who has warned that ditching the policy would lose voters.
Simon Hughes, the former party president, also insisted yesterday: "There are other ways we can find savings."
Sir Menzies, who is Chancellor of St Andrew's University, told the meeting that he strongly supported the principle of free education, but added that Lib Dems could not disregard the crisis facing the nation's finances.
He said: "In these circumstances I don't believe there can be any sacred cows."
Sir Menzies argued that the Lib Dems had to consider the choice between "giving a benefit which up to now people don't have or deciding whether to cut services to the leading edge of the National Health Service".
He added: "For me, that's not really a dilemma. "The importance of the NHS or primary school education is so paramount. Therefore it would be perfectly legitimate for us to conclude that we postpone a highly desirable policy in order that we continue to meet absolutely essential objectives."
Sir Menzies forecast that President Barack Obama would announce plans to withdraw US troops from Aghanistan within two and a half years. "He won't want to fight the next election for president, or even to begin the campaign, as someone who has committed the US to a long-term engagement."
Sir Menzies, who quit as leader in 2007, blamed his poor performances at Prime Minster's Questions on having too many people advising him on which subjects to raise in the Commons.
"I had too many advisers at one stage. That was my fault, not theirs. They all want their 10 pence worth," he said. "I stopped taking advice on the questions in the end and made up my own mind."
He hinted that his party colleagues responsible for forcing his resignation had wanted the home affairs spokesman, Chris Huhne, to replace him but had been disappointed by Mr Clegg's victory.
"One or two didn't get the leader they wanted," he said, but refused to reveal any names.
The former leader said he regretted that he had not been given the opportunity to lead his party into a general election, when he believed he would have "come into my own".
However, he admitted that he had no choice but to step down when colleagues advised him that he could not weather the criticisms over his age and leadership style.
"It became clear to me that there wasn't going to be any respite to this question of age," he said. "I asked close colleagues if they thought I could trade my way out of it. They said they thought I couldn't."
Sir Menzies was also asked about the departure of his predecessor as leader, Charles Kennedy, who stepped down after admitting to problems with alcohol. "I think it was at our party conference in 2005. It seemed to me that he had reached a point that it would be difficult for him to carry on," he said.
"I went to see him and said, 'Look, you've got the best result of any party leader since 1931, you've got a beautiful son and wife. You could in all honour now say you're going to step down. He didn't feel like he could do it at that point."
A podcast of Sir Menzies Campbell in conversation with Steve Richards: independent.co.uk/live