At yesterday's Liberal Democrat conference in Brighton, Paddy Ashdown was warned that he will have to break off his close links with the Government if Mr Blair fails to deliver on PR.
It has emerged that senior ministers opposed to PR are demanding the referendum be delayed. Mr Blair is considering their call as he searches for a policy that will unite his Cabinet, which is divided over electoral reform.
The Prime Minister is expected to back next month's report by a commission chaired by Lord Jenkins of Hillhead, the Lib Dem peer, for general elections to be fought under the "alternative vote plus" system. Voters would elect 500 constituency MPs, who would be "topped up" by about another 100 chosen to reflect each party's proportion of the total vote in each area. However, there are growing doubts in the Cabinet that Mr Blair will put the Jenkins plan to a referendum in this Parliament.
"There is no guarantee we will find time for it," one minister said last night. "We have a heavy constitutional programme and this will have to take its place in the queue. A referendum might not be something you would risk shortly before a general election."
It is understood that Jack Straw, the Home Secretary, John Prescott, the Deputy Prime Minister, and Gordon Brown, the Chancellor, want Mr Blair to shelve the referendum until the next Parliament. They argue that this would give the Government time to see how different PR systems operate in upcoming elections for the European Parliament, the Scottish and Welsh assemblies and the London mayor and assembly.
The Cabinet rift compounds the internal rebellion facing Mr Ashdown, who was given a stern warning by his party yesterday that his strategy of close co-operation with Mr Blair risked turning the Lib Dems into "Labour's lapdogs".
Criticism of Mr Ashdown's policy of "constructive opposition" dominated the second day of the conference as Simon Hughes MP delivered a withering attack on the idea of "cosying up" to Labour. Mr Hughes, the party's health spokesman, and Charles Ken-nedy, its agriculture spokes-man, said that co-operation should be strictly limited to constitutional reform.
If the Prime Minister refused to back a proportional voting system, the Lib Dems should pull out of the cabinet committee on the constitution and abandon any form of support for the Government, they said.
Mr Hughes and Mr Kennedy caught the mood of the conference at a packed fringe meeting when they attacked Labour for abandoning the poor and warned their leader not to ape government policy. Mr Hughes said Mr Blair's response to the Jenkins Commission was the "big test" of the policy of constructive opposition.
"I think there have been occasions in the past when we have wobbled and been tempted to water down what we said in order to keep the Government happy. We are not their lapdogs, we are not their poodles," he said to loud applause.Reuse content