Image caption Adam Price (L) and Rhun ap Iorwerth have declared their candidacy for the Plaid Cymru leadership

Adam Price and Rhun ap Iorwerth are to challenge Leanne Wood for the leadership of Plaid Cymru.

Both senior AMs announced their candidacy on Wednesday, triggering a contest in the party.

Ms Wood, leader since 2012, had said she would welcome a challenge and was very confident of winning.

It means a leadership contest is now underway in all but one of the parties represented in the National Assembly.

There have been mounting calls within Plaid Cymru for a leadership challenge, with a window for potential candidates closing at midnight.

Mr Price said calls for change could not be put off, while Mr ap Iorwerth called for a debate that would "energise the party and the country".

Former MP Mr Price had said on Monday he would not challenge Ms Wood for the leadership if she agreed to share the job.

But on Tuesday Ms Wood rejected the proposal and said it was a matter for the membership.

Image caption Leanne Wood has been leader of Plaid Cymru since 2012

Launching his campaign, Mr Price said his proposal "remains a practical and progressive way forward and it could have made a traditional contest avoidable".

"However, media statements soon indicated the negotiations were being undermined," he said.

"So we must park the proposal for the time being and revert to established procedure."

Mr Price added: "We cannot put off the irresistible call for defining change.

"Change in the way we frame our politics; the projection of who we are, what we stand for, what we have fought long and hard for and what's ultimately important to us."

Media playback is unsupported on your device Media caption Rhun ap Iorwerth: "Leanne herself has invited that challenge"

Mr ap Iorwerth was the first to launch his campaign, via a social media video on Wednesday, saying Ms Wood had invited a debate on the leadership and that supporters and party members across Wales had "encouraged me to allow my name to go forward".

He said: "That encouragement has come from people at all elected levels, but mainly from ordinary party members, including some who, I'm quite sure, will back Leanne!"

Mr ap Iorwerth said he was accepting the nominations in the spirit of a "constructive debate" that can "energise the party and the country".

"My commitment is to Wales, and to a fairer and more prosperous future for the country," he said.

"Plaid Cymru has to lead the way to that new, confident Wales".

Analysis by Aled ap Dafydd, BBC Wales political correspondent

Image caption Both Adam Price and Rhun ap Iorwerth had been urged by their local parties to stand

Something has not been connecting for Plaid - we have not seen the electoral earthquake predicted by Adam Price, the tectonic plates haven't shifted to any degree.

That has led to a growing sense of malaise in the Plaid Cymru assembly group. Some wanted Leanne Wood to move away from niche issues, others think the only way to power is to extend a hand to the Tories.

It just became apparent that people wanted different things and the leader couldn't accommodate.

My sense is that both rival candidates would rather it hadn't come to this.

Plaid's pivotal moment

Before joining the assembly, Mr ap Iorwerth was a reporter and presenter for BBC Wales, and presented Newyddion 9 on S4C.

He became an AM in a by-election in 2013, succeeding former Plaid leader Ieuan Wyn Jones who stepped down from the assembly to run a science park.

Earlier in June Mr ap Iorwerth told a press conference that he had "no plans and neither does anyone else have plans to put their name forward in that particular window".

Mr Price was an MP for Carmarthen East and Dinefwr from 2001 to 2010.

An attempt he and other MPs made to impeach Tony Blair over the Iraq War in 2004 failed.

After voluntarily leaving the Commons in 2010 he embarked on a Fulbright scholarship at Harvard University. He was elected to the Welsh Assembly in 2016, once again representing Carmarthen East and Dinefwr.