Portsmouth Labour candidate Syd Rapson revealed his embarrassment after one of his backers was accused of throwing an egg at John Major.
The Labour party was poised to take action against a Portsmouth Polytechnic student if he was convicted of the offence under the Public Order Act.
Mr Rapson, the Labour challenger for Portsmouth South, said: ‘I am very much embarrassed that he was one of my 30 nominators.
I condemn totally anybody who resorts to such actions.
‘This sort of behaviour is completely intolerable, and the Labour party totally dissociates itself from it.
‘Anybody who undertakes violent protest has no place in the Labour party.’
The student in question, aged 25, would face expulsion from the party if he was found guilty. He was given police bail to appear before Eastleigh magistrates.