Parents in the London borough of Wandsworth are to challenge the Government by standing on a "no-selection ticket" against Labour candidates during the May local elections.
The parents say they have been betrayed by Education Secretary David Blunkett's pre-election rhetoric and post-election policy.
Their pressure group, the Campaign for Local Education, says the Government will allow schools to select pupils, despite Mr Blunkett's recent declaration that "part of our admissions policy will remove partial selection where it exists".
They are campaigning against Clause 91 of the School Standards and Framework Bill, which permits partial selection where it already exists. The Bill also allows all schools specialising in particular subjects to select 10 per cent by aptitude.
Wandsworth, south London has been targeted as one of the previous Tory government's flagship authorities. It is one of Labour's key targets and a split in the vote would be damaging. Mr Blunkett's office was immediately informed of the challenge by Wandsworth Labour party leadership.
There are 10 secondary schools in the borough; all select their pupils to some degree. Three have a banding system taking 20 per cent of pupils from each of five ability bands. Two Roman Catholic schools select by interview. This means children can take up to seven tests in order to get a place.
The parents' group is to field eight No Selection in State Education candidates in the eight wards with secular secondary schools.
A Liberal Democrat amendment to end partial selection was defeated by the standing committee on the Bill. Education spokesman Don Foster had outlined the problems partial selection created in areas such as Wandsworth and Bromley, south London.
He said: "Partial selection has taken place not through direct legislation, but through circulars which are not authoritative legal interpretations of the law. The Bill puts partial selection into statute and gives it the full force of law."
During the debate education minister Estelle Morris said where partial selection caused chaos, a local adjudicator, who will rule on admissions and school organisation, will be able to take appropriate steps.