Vince Cable ally Lord Oakeshott calls on Nick Clegg to quit as leader before next election

Outspoken Lib Dem grandee Lord Oakeshott wants to prevent voter backlash in 2015

The Liberal Democrats should consider ousting Nick Clegg as their leader ahead of the next General Election, a senior party figure said yesterday.

Lord Oakeshott, a close ally of the Business Secretary, Vince Cable, called for the "strategy and management" of the party to be reviewed in order to head off a bloodbath at the 2015 election. He said: "Elections are not just about the message. They are also about the messenger."

Clegg allies accused Lord Oakeshott of disloyalty. Although he is an outspoken critic of the leadership, his criticism was a setback for Mr Clegg, who tried to calm his party's jitters this week by proposing a temporary wealth tax on the rich.

There is no organised plot to oust the Liberal Democrat leader. But his critics believe his position will be discussed in the margins of the party's autumn conference in Brighton next month. They say he could come under pressure to promise to stand down before the next election if the Liberal Democrats suffer another rout at next May's local elections.

In an attempt to head off any such move, Lord Ashdown, the former Liberal Democrat leader, today issues a plea to the party to rally behind Mr Clegg and avoid "short-term manoeuvring." Writing in The Guardian, he praises Mr Clegg for challenging the party to leave its "comfort zone" in opposition. But his appeal will be seen as a sign that the threat to the leader's position is being taken seriously.

Lord Oakeshott told BBC Radio 4 that progressive policies were needed to win back tactical voters who had backed the Liberal Democrats to stop Conservatives winning key marginal seats. He said 39 Liberal Democrat MPs defending seats where Tories were runners-up would struggle to hold on in 2015 unless Labour supporters backed them again.

"We have lost over half our market share, if you like to put it that way if we had been Sainsbury's, since the election and any business that had done that would be looking very hard at both its strategy and its management to see how we get some of that back, because otherwise we are going to lose a large number of seats," he said.

Lord Oakeshott added that the challenge was "not just to put the message across but to get it implemented in government" – an implicit call for Mr Clegg to fight harder for Liberal Democrat ideas inside the Government. He believed voters were not against a coalition, but did not like the Liberal Democrats being in coalition with the Conservatives.

Mr Cable, who insists that at the age of 69 he is not too old to lead his party, has kept lines open to Labour and is seen as having more appeal to centre-left voters than his party leader.

Clegg allies insisted he was relaxed about Lord Oakeshott's latest intervention. One Liberal Democrat source said: "He [Lord Oakeshott] does not necessarily think of the interests of the party. To use his own business analogy, if someone is running a company which after 60 years achieves its core purpose, as we have done by going into government, that person is probably owed a bit of loyalty."

Mr Clegg hit back at Lord Oakeshott, telling ITV News: "In politics you always have back-seat drivers who sit there making endless comments about people who have to lead."

The Lib Dem leader's critics believe party members will decide his fate. Growing disquiet at grassroots level emerged in a survey of 500 members by the Liberal Democrat Voice website last month, which found them evenly split on whether he should lead the party into the next election.