Plaid Cymru leader Leanne Wood has called for political parties to unite to work towards restoring gender balance in the Senedd.

Ms Wood has written to Rosemary Butler AM, the National Assembly for Wales’s Presiding Officer (PO) asking for her support on establishing cross-party consensus on the best ways to encourage more women politicians. In her letter, Ms Wood raises the question of whether new legislation is needed to bring about the change.

The number of female Assembly Members has dropped with every election since 2003 and now stands at just over 40%. This compares to the 50/50 split reached following the 2003 election when Ms Wood was first elected as a regional Assembly Member for South Wales Central.

When the gender balance was more equal, a report by Swansea and Warwick universities argued other legislatures should emulate the Welsh example as debates were more consensual than adversarial and plenary sessions covered less traditional subjects such as domestic violence.

Ms Wood’s comments are in response to a plea from the PO urging action from all political parties to increase women’s participation in Welsh politics

In her letter to the PO, Ms Wood says: “In carrying out your mandate from the Women in Public Life conference, you have made an important public contribution to the debate ahead of the next Welsh General Election in 2016.

“In your comments, you noted the fact that our once world-leading levels of women’s representation have declined in the National Assembly since 2007. The responsibility for addressing this decline lies with the four political parties most likely to secure seats in the Assembly.

“But all four parties have their own selection processes for determining candidacies, that in our case have to balance the rights of the party membership with any positive measures we might also put in place.

“Within Plaid Cymru, we have a strong internal democracy which reflects how much we rely on the party membership as a grassroots body. The side-effect of this is that measures to promote women are not always at their strongest, but must be balanced out with local party control.

“Over the years we have also seen that this is true outside of Plaid Cymru as well, as tensions between local party democracy and central party machines have been apparent in other parties.”

Ms Wood says it may be the case that legislation is required to create a more representative democracy in Wales. Ahead of powers being devolved to the Assembly, Ms Wood suggests that Westminster is lobbied to draft the new legislation.

“I believe that by approaching the four party leaders you could determine whether a consensus can be established around how to move forward with regards the selection of women, and whether for example, there is a need for legislation in this field,” said Ms Wood.

“We could of course only move forwards toward legislation for gender equality in Assembly representation, if and when a consensus is forged and if the powers to legislate are devolved, although in the meantime we could request that legislation is amended in Westminster.

“In my capacity as Plaid Cymru leader, I believe that the National Assembly, as an equal opportunities employer and as the representative body of the people of Wales, would have a credible basis upon which to take action to ensure that political parties contesting elections have a duty to reflect the gender balance of the Welsh nation across their range of prospective candidates.

“The institution is in a position to help shape the approach that the parties take towards selecting their candidates. An approach led by the Commission would be seen as being above narrow party interests and could lead to equal rules being evenly implemented across the parties, or at least the existing Assembly parties.

“Beyond setting out these principles, it would be necessary of course to consult widely and ensure that any proposals are fully scrutinised. At this stage, exploring the possibility of a consensus would be a credible step forward, and I look forward to hearing your thoughts on this.”