The NUT, the largest teaching union, rejected a vote by delegates at its conference in Harrogate at Easter to hold a ballot on strike action.
But yesterday the union's alternative to the strike - to launch a joint campaign with another union against the government's plan - immediately hit the rocks.
A spat developed between the union and its would-be partner the National Association of Schoolmasters/Union of Women Teachers.
Nigel de Gruchy, general secretary of the NAS/UWT, demanded an apology from his NUT counterpart, Doug McAvoy, for what he called an "outrageous accusation in his conference report that we were supporting the government on performance-related pay".
Mr de Gruchy said: "There is no question of us giving consideration to a joint campaign unless he retracts that statement and issues an apology."
Mr McAvoy had announced yesterday that a joint meeting would be held with the NAS/UWT on Tuesday, the day after the deadline for applications by classroom teachers for performance-related pay.
Delegates at the conference had voted by a 60-40 majority to hold a ballot. But the executive believed the rank and file membership would vote no in a ballot.
A survey of members produced a 30% response rate and only three out of five participating wanted a strike. A legal challenge in Wales to performance-related pay may also be successful.
The NUT's executive said other teacher unions had made it clear the NUT would be isolated if it went on strike. "Division in the profession and the probability that a significant number of NUT members would vote no would allow the government to claim that only a minority of teachers opposed performance-related pay."
The government is promising classroom teachers with no extra duties, earning £23,958, at the top of their pay scale, an extra £2,001 from September. Eventually their pay could increase to £30,108 on the new threshold. The NUT has recommended its members apply for the offer although it opposes it on principle.
David Hart, general secretary of the National Association of Head Teachers, welcomed the NUT executive's "very wise decision".
But in his speech to the NAHT's conference in Jersey, he attacked the "depressing message" sent out by the NUT conference. Heads of department had to have a role in assessing the performance of teachers under them, he said.
"To engage in behaviour they would deplore in their own pupils, to insult their own senior members by talking about snooping on fellow teachers as a description of threshold assessment, to refuse to debate professionally, gives an image which damages the standing of the profession," Mr Hart said.
Useful links
National Union of Teachers
National Association of Head Teachers
