Conservative leader David Cameron has announced new measures to make local associations put more women on their candidate selection shortlists.
David Cameron wants to see more female Tory MPs in Parliament
Mr Cameron's initial measures have seen women candidates selected in a third of winnable seats, but he says the party must go "further" and "faster".
So he now wants two of the final four candidates short listed for selection in each constituency to be women.
Mr Cameron said he would review whether more action was needed later this year.
He did not rule out the idea of imposing all-women shortlists, which were used by Labour.
But he said he thought they were a "step too far".
"The problem with all women shortlists is you are really denying the ultimate choice to the constituency," he said.
In a further change, all local Tory associations with fewer than 300 members will have to hold a US-primary style contest where any local voter has a say in choosing the final candidate from a shortlist.
Larger associations will also be allowed to use this process. A further option will be for local associations to choose to have women-only shortlists.
But the new standard process will be for grassroots Tories to select a shortlist of four, including at least two women, with the final selection made by the local association's executive board after "rigorous and professional" job interviews.
Mr Cameron said the change - effectively reversing the previous process - would mean grassroots members were involved earlier in the process.
But some activists will feel angry they will no longer have the final say on their local candidate.
Mr Cameron is increasing the proportion of women on his priority list of 150 candidates from 50% to nearly 60%.
At the moment less than a tenth of Conservative MPs are women.
Mr Cameron said he was encouraged that the proportion of women selected as candidates under the new process was already three times more than the current share of women Tory MPs.
But he wanted to accelerate that progress.
"This is an issue about fairness, it is an issue about quality but for me it's also an issue about effectiveness," said Mr Cameron.
"If we do not have proper representation of women and black and ethnic minority candidates in Parliament, we will be missing out on huge amounts of talent."
Former Tory minister Ann Widdecombe said giving women preferential treatment would create "two classes of women in Parliament".
Conservative chairman Francis Maude told BBC Radio 4's Today programme the latest measures amounted to "positive action" rather than positive discrimination.
"What we're showing is that by incremental change, you can actually show that the party is itself changing from within without that need for that kind of compulsion," he said on the BBC Radio 4 Today programme.
Since Mr Cameron took over, seven out of the 22 candidates selected (32%) have been women. Two (9%) have been from ethnic minority backgrounds.
Labour chairman Hazel Blears said the latest measures showed Mr Cameron was failing to change the Tories.
"This step is Cameron's latest, but probably not last, admission that the Conservative Party are still failing women," she said.
"In his speech to the Conservative Spring Forum, David Cameron said that the test of whether change in the Conservative Party was real and lasting lay in 'the candidates we select'."
For the Lib Dems, Norman Lamb said: "This is yet another Cameron initiative of style over substance... he may beg Tory constituency associations to select more women, but he is not going to offer them any direct incentive to do so."