Ex-Conservative chief executive Barry Legg is mounting a fightback against plans to change leader election rules.
Mr Howard will stand down before Christmas
Based along the road from Conservative HQ in London, the Better Choice campaign wants the party membership to decide Michael Howard's successor.
Last week Tory MPs backed a change which would give them the final say.
Mr Legg says his grassroots campaign has already won the support of 100 local chairmen and he is in the process of contacting all Tory associations.
"This is about reacting to the [Conservative ruling] board's proposals. We want to make sure that the board doesn't take an excessive amount of power to the centre," he told the BBC News website.
He added that a modern Conservative Party should not ignore the wishes of its members who were perfectly capable of judging what qualities a leader should have.
Asked about the decision of party members to elect Iain Duncan Smith over Ken Clarke during the last contest, ex-MP Mr Legg said they had made the choice according to the two shortlisted candidates they were offered.
Mr Legg said his campaign to retain the current leadership election system was not about favouring one candidate over another.
Tory MPs last week backed by 127 votes to 50 a change in party rules for electing their leader.
Conservative MPs opposing the plans included potential leadership candidates Theresa May, Michael Ancram, David Willetts and Andrew Lansley.
The proposals, already agreed by the party's ruling board and senior backbenchers, would give Tory MPs the final say in the coming contest.
The new system would mean grassroots members only being consulted, rather than having a vote.
The plans will now be drawn up into a formal amendment to the Conservative Party constitution to be put to a convention.
Conservative members had already rejected Michael Howard's plan to allow party chairmen to rank candidates before a binding ballot of MPs.
The current rules were introduced by former Conservative leader William Hague.
Other potential candidates for a Tory leadership contest expected in October include David Davis, Kenneth Clarke, David Cameron, Sir Malcolm Rifkind and Liam Fox.
Mr Legg was appointed party chief executive by Mr Duncan Smith but stepped down after three months in the job after "a strategic review of the organisation and operation" of central office by the Conservative Party Board.