By Gary Eason
BBC News Online education editor
Grammar school head teachers in England are setting up a new group to give themselves more "clout".
More than two thirds of the heads attended a preliminary conference
A constitution and action plan are to be drawn up at a special meeting scheduled for next Monday.
The new organisation would be part of the National Grammar Schools Association (NGSA).
The NGSA represents the wider interests of the remaining 164 grammar schools, including the views of governors and parent-teacher associations.
The new group is expected to be launched formally at the Royal Grammar School in High Wycombe, Buckinghamshire, in November.
The headmaster there, Tim Dingle, described it as being akin to the HMC - the Headmasters' and Headmistresses' Conference, which represents the principals of the leading fee-paying schools.
It would feel "able to be more political" than the NGSA, he said.
The NGSA's chairman, Brian Wills-Pope, said two preliminary gatherings had been very successful, with 50 or 60 heads at the first and 110 at the second.
"They felt this was a very positive move because there isn't a forum in which grammar school heads can get together nationally."
He added: "It's to make the heads a stronger part of the NGSA and if you like feed more into it, so it would have a stronger lobbying organisation as well."
He said he was not too sure too many heads would want to be more political - that would depend on their relationship with their local education authorities.
But they had delivered "another good set of results" in this year's exams.
Mr Wills-Pope, chair of governors at Torquay Boys' Grammar, said: "They are good schools."
Many were on a par with the more academic independent schools, without the price tag.
"If you have a bright youngster and you are not so well off there's an opportunity for you, and I think a lot of Labour voters realise that."
For that reason, he believed the government was wary of alienating many supporters in more marginal constituencies.
But events in Gloucester had shown that some grammar schools were still vulnerable to attack "by the back door".
Labour and Liberal Democrat politicians in the city are proposing a reorganisation of local secondary schools which could put at risk the future of the four grammars there.
They argue that change is necessary because too many local children are "not reaching their potential".
Mr Wills-Pope was buoyed by remarks by the shadow education secretary, Damian Green, in his address to the Conservative Party conference on Monday.
Mr Green said a Tory government would support the existing grammar schools and more of them might be established.