A maths teacher set to stand for the British National Party (BNP) in June's European elections has been suspended by his school.
Simon Smith, a teacher at St Peter's Roman Catholic School in Solihull, has been chosen as a candidate for the far-right party in the West Midlands Euro constituency.
The NASUWT threatened disciplinary action against any member associating the union's name with the party.
The news came as heads of major churches across West Yorkshire gathered in Leeds to sign a ìhistoric joint statement deploring the racist policies of the BNP and calling on Christian people to use their voteî.
It also follows the launch last week by the Methodist church of "Countering Political Extremism" an online information resource for any church or other groups concerned about the rise of far-right political parties such as the BNP.
Dr Phil Edwards, national press officer for the BNP, said: "The union don't pay his wages, they don't employ him.
"Who do these people think they are. If he does his job well and is a committed teacher they shouldn't be using the power of the media to intimidate him or his employer.
"He is an exemplary teacher, he is clever, a graduate, a decent bloke and just like other people in the BNP he would not pick on anybody of another race just because of that."
The BNP's website lists Mr Smith as its second candidate for the West Midlands constituency in the 10 June elections.
Deputy general secretary of the teaching union, Chris Keates, said NASUWT policy was that BNP membership was in breach of the objects of the association.
"We have a clear policy on this issue endorsed at our national conference last month," she said.
"NASUWT abhors and condemns the policies and activities of the BNP and the sooner legislation is enacted to enable us to expel from membership anyone found to be involved in BNP activities, without them being able to claim compensation, the better."
Mr Smith is not believed to be a Catholic and is employed full-time by the school on a one year contract.
The schools commission for the Archdiocese of Birmingham also supported the suspension.
A spokesman for the archdiocese said: "It came as a complete shock to the school," he said.
The Archbishop of Birmingham issued a statement outlining the church's guidance on the forthcoming local and European elections on Wednesday morning.
It said Roman Catholic voters need to be confident that the candidate they vote for recognises the equal value of all people.
The Most Reverend Vincent Nichols, Archbishop of Birmingham, said: "I would not expect anyone who did not support these values to be given a permanent position in a Catholic school.
"This is because a teacher in a Catholic school must support the values and ethos of that school."