LONDON (AP) ― Britain’s government is pushing its plan to change the rules on royal succession to provide equal treatment for princes and princesses, the prime minister said Wednesday.

David Cameron said he has written to 15 other Commonwealth nations where Queen Elizabeth II is head of state requesting their views on modernizing succession.

Under the proposal, the first child of Prince William and the Duchess of Cambridge would eventually become monarch ― regardless of sex. As the law stands now, an elder daughter would be passed over in favor of a younger brother. “We espouse gender equality in all other aspects of life and it is an anomaly that in the rules relating to the highest public office we continue to enshrine male superiority,” Cameron wrote in his letter.

The changes would also lift a centuries-old ban on British monarchs marrying Roman Catholics ― a rule Cameron described in his letter as a “historical anomaly” since it does not bar those who take spouses of other faiths. “We do not think it can continue to be justified,” Cameron said.

Cameron said he will be discussing the proposals when he meets with leaders from Commonwealth countries at a summit in Australia later this month.

“It isn’t an easy issue to sort and for many of them there might be issues and worries about starting a parliamentary or other legal process,” Cameron told British lawmakers. “But I am very clear that it is an issue we ought to get sorted and I would be delighted to play a role in doing that.”

Buckingham Palace has always refrained from commenting on the political issue, saying it’s a matter for the government.

The prime minister’s office said the queen would not be part of the discussions.

Pressure to change the laws of succession has been mounting since William’s marriage to the former Kate Middleton in April.

The thorny issue of succession has been an on and off topic in Britain, but it has never been resolved. In 2009, then Prime Minister Gordon Brown’s government considered a bill that would end the custom of putting males ahead of females in the succession line, as well as lift the ban on British monarchs marrying Roman Catholics. The government did not have time to pursue it before Brown left office.

The rule has kept women from succeeding to the throne in the past. Queen Victoria’s first child was a daughter ― also called Victoria ― but it was her younger brother who succeeded to the throne, as King Edward VII.

Experts say they hope the matter will be resolved before Middleton begins having children to avoid a confusing line of succession like that in Sweden, where a rule change led to a title being passed from a prince to his elder sister.

Downing Street has previously acknowledged that elements of the 1701 Act of Succession, which also bars Roman Catholics from succeeding to the throne, were “discriminatory” but said change would be “difficult and complex.”