Fawzi Ibrahim, an Iraqi Jew, and honourary treasurer of Natfhe, the lecturers' union, is standing as a by-election candidate, appealing to would-be Labour supporters who were against the invasion.
The by-election will take place later this year in Brent East after the death of Labour MP Paul Daisley in June. The seat was previously held by Ken Livingstone, after the Greater London Council was abolished under his leadership.
Mr Ibrahim, 60, an electronics lecturer at the College of North West London, says he has never been a Labour party member, but sees his position as a left-of-the centre alternative.
His unpaid position in the union involves scrutinising the way it spends its money, on behalf of its members.
Natfhe is unable to officially support or make payments to his election campaign but, he says, he has received donations in "four figures", almost entirely from Natfhe members.
The Labour party candidate, Robert Evans, a former school headteacher, is also a London MEP.
Mr Ibrahim said: "People are saying they are fed up with Tony Blair's smugness and arrogance. We want to give them a slap to get the Government in the right direction.
"But I do not accept that I am splitting the vote. It is Robert Evans who is splitting the vote by not speaking out openly against the war."
Natfhe and its activists have been closely associated with the campaign against war on Iraq. Both Mr Ibrahim and Paul Mackney, its general secretary, have spoken out at rallies.
Another lecturer, Uzma Bashir, 32, quit her job at West Herts College in Watford to become one of the "human shields" - protesters who positioned themselves near potential military targets in Iraq in an effort to prevent them being bombed by the US and UK coalition.