Blair wants Mayor Ken to serve out his ban from party

Tony Blair will seek next week to block growing demands for Ken Livingstone to be allowed an early return to the Labour Party fold.

The Prime Minister, who has faced an agonising dilemma over whether the Mayor of London should be readmitted to the party, has decided that he should serve the full five-year ban imposed on him for running as an independent candidate two years ago.

However, Mr Blair faces a knife-edge vote on the issue when Labour's ruling national executive committee (NEC) discusses the issue next Tuesday. Although the Prime Minister normally commands a big majority on the 32-strong committee, it is split down the middle on whether to allow Mr Livingstone to rejoin the party.

The turmoil in the trade union movement and the unions' growing hostility to the Government could boost Mr Livingstone's prospects of winning the crucial vote.

Opinion amongst grassroots Labour members is also said to be showing strong backing for Mr Livingstone. But Mr Blair and Charles Clarke, the Labour chairman, are understood to have decided that it would be wrong to make him a special case by shortening his ban.

"If he were an ordinary member, five years would mean five years," one minister said yesterday. "We shouldn't reduce the ban just because someone is good on television."

A possible compromise is being discussed in Labour circles in an attempt to prevent a split in London's Labour Party.

Under the plan, Mr Livingstone would not be readmitted to the party and Labour would select its own candidate for the next mayoral election in two years. But Labour would urge voters to cast their second votes for Mr Livingstone because the Mayor is elected by the supplementary vote, under which people select their first and second preferences. This would be a halfway house which could pave the way for Mr Livingstone's eventual readmission to Labour.

The NEC will in the future be changing the system under which the Labour Mayoral candidate is to be chosen.

London MPs and Greater London Assembly candidates, who had a third of the votes last time, will no longer form part of the electoral college. Half the votes will go to London Labour members and half to trade unions.