Business Secretary Vince Cable has challenged Nick Clegg over a core economic policy by calling for bigger tax increases to pay down the deficit.
In a direct contradiction of his leader, Left-leaning Mr Cable called for a “rebalancing” of the amount of tax rises compared with spending cuts.
His comments were quickly slapped down by sources close to the party leadership, who said they represented his personal view and not the “settled” policy of the party.
But Mr Cable’s intervention, just ahead of Mr Clegg’s keynote speech, fuelled the impression that senior Liberal Democrats are positioning themselves for a possible leadership battle.
Health Minister Norman Lamb confirmed he hopes to succeed Mr Clegg as leader, though he said he is a strong supporter of the embattled incumbent: “When he stands down, I haven’t ruled out standing for the leadership myself. In the meantime I think he has performed brilliantly in government, securing this country’s economic future.”
Other probable contenders who have attracted attention in Glasgow this week include Danny Alexander, the Treasury Minister, and Tim Farron, the party president.
Mr Cable made his inflammatory comments on BBC Newsnight, where he said it was “virtually inconceivable to me that we could do anything else but face some increase in taxation”.
He went further by saying there should be “a better mixture” of cuts and tax rises. Under the Coalition, there was an 80-20 ratio, meaning that four-fifths of the deficit reduction was achieved by cutting spending.
Mr Cable said: “I think it’s highly probable we would want to rebalance that and have a better mixture of tax as opposed to spending reductions.”
Asked if he would back a 70-30 or a 60-40 ratio, Mr Cable said: “I wasn’t naming a number, but certainly directionally that is right.”
But Mr Clegg insisted on Monday that he was wedded to the “80-20” formula. A senior Lib Dem source added: “We have made very clear we are not shifting from 80-20. It has been clearly set out by Nick Clegg and Danny Alexander.” The policy was respected by the financial markets and would not change, he said.
