The Conservative party leader will announce a change in selection procedures to ensure that women reach constituency association shortlists.

Although he will stop short of introducing all-women shortlists — used by Labour but fiercely opposed by most Tories — he is expected to say that the targeted local associations must ensure at least one woman reaches the final stages of selection.

He will also encourage parties to adopt more American-style primaries, in which nominations are thrown open to a wider audience than the usual core of activists.

Cameron will outline the moves tomorrow after a review into whether his controversial “A-list” of preferred candidates is working. Half the original list of just over 100 “priority” individuals were women.

However, an analysis of candidates selected since the A-list was introduced suggests it is being ignored by many local party associations, with less than a third — seven out of 22 — choosing women.

A total of 12 selections have come from the A-list, but 10 associations have bypassed the list. Of the 10 non-list selections, nine have been men.

The list is supposed to promote the selection of women and other groups, such as ethnic minorities, who are under-represented on the Tory benches.

Local party associations in London and the southeast appear particularly reluctant, with no women selected for the most winnable seats.

“The current priority list has improved the situation dramatically, but there is a recognition that more needs to be done,” Cameron’s spokesman said.

“We do not think forcing candidates on local associations is the way forward, but we do have some proposals for changing selection procedures to ensure that women are reaching the final stages.”

Cameron will also announce that the A-list has been “topped up” with a new batch of candidates, a greater proportion of whom will be women.

The total list, increased from 100 to about 150 names, will be 60% women.

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