Nick Clegg is giving himself unprecedented powers over the Liberal Democrats in the most wide-ranging revision of the party since its formation in 1988, The Times has learnt.

He is determined to overhaul an internal structure that allies say severely curtails the powers of the leader and splits internal controls between a series of committees.

Mr Clegg, who became leader in December, plans to turn the party's traditional structure on its head, centralising all decision-making under a new “chief officers group” and diluting the roles of its committees.

Sources said that the move risks causing a serious rift between Mr Clegg and Lord Rennard, the party's chief executive and the man in overall charge of the Liberal Democrats' election campaigns. Under the shake-up Lord Rennard will become a non-voting member of the group and will report to the party leader.

Mr Clegg is understood to believe that the existing mesh of committees is too unwieldy and needs to be streamlined if the party is to have any chance of meeting its goals, chief among them doubling the number of Liberal Democrat MPs in the next two elections. “There is a multiplicity of committees in the name of transparency, but ultimately what happens is you don't get any decisions being made at all,” one senior party insider said yesterday. “There are no clear lines of responsibility and accountability,” the source added.

The Liberal Democrat constitution is a throwback to the 1988 merger of the Liberal and SDP parties and leaves the leader without ultimate control. The SDP leader then, David Owen, opposed the merger and was suspicious of the Liberals' decentralised structure. While some effort was made to centralise power in the merged entity, many of the old Liberal Party structures remain.

Supporters of the changes argue that the party has evolved since then in terms of its size and influence but that its organisational structure has stayed stuck in the 1980s. Others will argue that Mr Clegg's move is a desperate power grab. Lord Rennard is understood to have strongly opposed the new structure.

Mr Clegg has already won support for his plan from the party's federal executive, which this week signed up to the plan and sent it out for consultation. The new chief officers group, which will comprise senior members of the party's committees, will be answerable to the federal executive.

Sources said that the aim was to introduce the new structure on a “suck it and see” basis, as an interim solution between now and the next general election. That way it can be introduced quickly as opposed to implementing the change via an amendment of the party's underlying constitution. “The new group will decide everything. In one sense, it may be overkill, but the basic thrust of it is right,” the source said.

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