David Hawker, Brighton and Hove council's head of children's services, is the official candidate for the National Association of Head Teachers' job.
He told The TES he may withdraw from the election, however, depending on the outcome of the union's extraordinary general meeting on the workforce agreement.
Mr Hawker said: "If the meeting voted to pull out, I would have to reconsider my position with the executive.
"I would need to look carefully at the reasons why they felt they should pull out, because as an incoming general secretary I need to know hand on heart that I can represent their views.
"My position on that (the agreement) is clear and if that is not what they want, then it won't be good for me, or for them, for me to be their general secretary."
Mr Hawker was selected by the union's personnel committee in December. But a large number of council members were unhappy at the decision, prompting a challenge from Mick Brookes, a former NAHT president.
This week, ballot papers were sent to more than 40,000 members asking them to vote for a replacement for David Hart, the union's general secretary, who leaves in September.
On Wednesday around 200 delegates, representing every local branch, association and region as well as the full national council, are due to attend the emergency meeting in London. They will vote on whether to endorse the NAHT council's November decision to stay in the workforce agreement.
The association has repeatedly threatened to pull out since signing the deal in 2003. The union's last conference in May voted that staying in should be dependent on the Government announcing "clear, adequate and direct funding" for the agreement by the end of the year.
But increasing numbers of primary headteachers say they will not have enough money to implement the 10 per cent planning, preparation and assessment (PPA) time guaranteed to teachers from September, without compromising standards.
Withdrawal from the talks would represent a double blow for the association's leadership, which as well as seeing its decision on the agreement overturned would lose its next preferred general secretary.
Mr Brookes, head of Sherwood junior school, Warsop, Nottinghamshire, will represent his local branch at the meeting which is calling for withdrawal from the talks, although he believes this should only be until enough funding is made available.
David Hart, the union's general secretary, believes withdrawal will "achieve absolutely nothing". He accepts there will be several hundred schools unable to implement PPA time, but believes the association needs to stay in talks to make its case to other partners.
"We have to say that this is not a simple question of implementing the agreement at all costs because that is totally and utterly unacceptable," he said. "But if we withdraw we will have cut ourselves off and we will not be listened to."
George Phipson, the NAHT's funding consultant, is expected to tell delegates there is enough money in the system nationally to fund the agreement but that some local authorities are not devoting the resources to it that they could.
Mr Hart believes the NAHT needs to concentrate on making local authorities rather than individual schools responsible for implementing the deal.
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