Mick Brookes, a Nottinghamshire junior school head and past president of the National Association of Head Teachers, is to challenge David Hawker, the education director of Brighton and Hove, who was selected last week by a sub-committee, after receiving advice from headhunters.
Mr Brookes has written to the union's 11 regional executives seeking their nomination for him to succeed David Hart as general secretary in September.
If three of them vote to back him by the January 21 deadline then a leadership election will be triggered.
Mr Brookes, NAHT president in 20001, said: "I don't think the right decision has been made. I think the union needs somebody working for it who has recent experience of working in a school."
Mr Hawker was selected by a majority of the seven-member personnel committee from three short-listed external candidates.
But a large number of national council members, who heard 20- minute presentations from all three, are understood to be unhappy with the decision. "People were underwhelmed by the candidates that we saw," said one who wished to remain anonymous.
But others do not want an election. Clarissa Williams, a personnel committee member, said: "I am concerned that it could create division in an association that has been so successful. We need someone who is robust and able to deal with education in the future."
Both Mr Hawker and Mr Brookes are against pulling out of the school workforce agreement over funding, another source of controversy within the NAHT.
Mr Brookes, who was one of more than 20 original leadership applicants, said he believed thousands of schools would be unable to implement the final stage of the deal in September. "The time is right for the association to be led by one of us," he said.
Mr Hawker did not want to comment on the prospect of an election.