Labour's devolution difficulties deepened last night, as veteran left-wingers Mr Dennis Canavan and Mr Ken Livingstone pledged defiance over selection procedures for the Scottish parliament and the candidacy for London's first directly-elected mayor.
Mr Livingstone's ambitions received a severe setback on Tuesday night when London Labour chiefs reversed an earlier decision that any candidate commanding the support of 10 constituency parties would automatically be put to the final vote of all party members in the capital.
The decision to opt for a "screening process" by selection panel was seen as confirmation of the leadership's determination to block Mr Livingstone's candidacy - while word emerged that Mr Tony Blair would like a senior business figure with proven executive abilities to come forward as the party's standard-bearer.
While insisting he would not leave Labour or stand as an Independent, Mr Livingstone pledged a massive grassroots "write-in" campaign demanding his inclusion on the final ballot paper should the selection panel exclude him from it.
The battle with the former chairman of the Greater London Council (GLC) could prove the biggest single challenge thus far to Mr Blair's authority.
Reminding people that, as leader of the defunct GLC, he had fought Mrs Margaret Thatcher "to the bitter end", Mr Livingstone said: "If they think it's going to be a three-day row and it is then going to fade away, they are kidding themselves."
Mr Livingstone planned to seek trade union backing for a "write-in" campaign which would involve at least one direct-mail shot at all 69,000 party members in London. If he was kept off the ballot paper, members would be invited to write him back on.
"If we can win the ballot that way, I think it will be impossible for them to refuse to endorse me," he said, adding that it would be "a humiliating defeat" for the person trailing "second" to be asked to be the candidate.
The Prime Minister's official spokesman defended the controversial selection processes now in operation in respect of upcoming London, Scottish, Welsh and European elections, insisting the party had a right to expect candidates to support its policies. He said: "I know you would like us to have candidates everywhere who spend their time slagging off the party but that's just not grown up."
However, with the London leadership's drive for discipline and control already facing resistance in Wales, Mr Canavan - now facing expulsion after declaring he would stand for the Scottish parliament as an Independent - characterised a "move toward Stalinist control" as completely contrary to "the declared aim of decentralising decision-making within the British state".