Plaid Cymru leader Leanne Wood has re-stated her aim to become Wales’ first minister, after a potential leadership rival asked her to share power.
Adam Price said he would challenge Ms Wood for the leadership if she did not agree to his plan.
Plaid rules allow a leadership challenge every two years, with Wednesday the deadline.
The party’s assembly group said rank-and-file members should decide whether to adopt a system of joint leaders.
There have been calls within the party for a leadership challenge, with former Plaid leader in Westminster Elfyn Llwyd calling for a change in direction and local constituency parties calling on both Mr Price and Ynys Mon AM Rhun ap Iorwerth to stand.
Three other Plaid AMs – Llyr Gruffydd, Sian Gwenllian and Elin Jones – have signed a letter calling for a competition.
On Monday, in a newspaper article, Mr Price said the party had resorted to “predictable, plodding politics”.
The Carmarthen East and Dinefwr AM said a male/female co-leadership was needed if Plaid was to win the 2021 election.
Following a Plaid assembly group meeting on Tuesday, Ms Wood said: “Wales faces huge challenges and that’s why we need a Plaid Cymru government more than ever.
“I want to lead this party with a positive platform into the 2021 election and I intend to become First Minister.
“I’ve set myself a high bar, and I’m putting my job on the line for it.”
The Rhondda AM, leader since 2012, said it was up to party members to decide if they were in favour of the party adopting Mr Price’s proposal.
“I am keen to discuss further how we can build a stronger collective leadership, and we need time to consider different options in a spirit of comradeship through the democratic processes of the party,” Ms Wood said.
“The membership must decide how we move forward to achieve our goals.”
Plaid AMs decided earlier on Tuesday that the question of co-leadership should be decided by party members.
A spokesperson for the group said: “Party leadership structures should always be considered for renewal and there is merit in exploring new ideas.
“However, the Group agreed that such proposals are a matter for the party and its membership, rather than the Assembly Group.”
It is understood that four of the 10 Plaid AMs were not resistant to the idea of having joint leaders when the group met.
Speaking before the meeting, group chair Dai Lloyd said people would understand a “conventional” campaign with a single leader, while Sian Gwenllian said the circumstances for co-leaders were not right “in this instance”.
In a tweet on Monday, Simon Thomas AM called on Mr Price to either support Ms Wood or take it to a leadership contest before Wednesday’s deadline.
“We tried this before and it was disastrous,” the Mid and West Wales AM said of the joint leadership idea.
“Adam was one of those who helped get the leadership structure right. Either back Leanne to lead or challenge her. There’s no easy route to the top.”