Headteacher Geoff Barton has gained enough support to challenge Chris Kirk for the leadership of the Association of School and College Leaders (ASCL).
Last month, ASCL announced that it had nominated educationalist Mr Kirk as its preferred candidate for the role of general secretary.
But today, as nominations closed, it was confirmed that Mr Barton, headteacher of the King Edward VI School, in Suffolk, has also been nominated as a candidate to lead the union.
The well-known headteacher, and regular TES contributor, received the support of around 230 full members drawn from 10 different branches of the association.
No election will be called until both candidates accept the terms and conditions of employment.
If an election is called, there will be a postal vote of full members in December and January - with the result announced in February.
Malcolm Trobe, interim general secretary, will continue to lead the association until the new leader is in post.
The Nomination Committee of ASCL Council, the association’s policy-making body, made its decision on education consultant Mr Kirk after carrying out an executive search.
As is required by ASCL’s constitution and by trade union legislation, full members of ASCL were invited to submit nominations for any other candidates.
TES revealed exclusively last month that Mr Barton planned to challenge ASCL's preferred candidate, Mr Kirk.