B.C. NDP veterans are taking sides as caucus members head to an emergency meeting Sunday in Vancouver.

Leader Carole James has called the meeting to head off a rebellion by 13 dissident members — more than a third of her caucus.

The situation was brought to a head this week by veteran MLA Jenny Kwan, who openly denigrated James's handling of the party and called for a leadership convention as soon as possible.

NDP Leader Carole James has said the most recent rift puts the very existence of the B.C. party at stake. CBC Former NDP cabinet minister Paul Ramsey has written an open letter, saying MLAs do not have the right to depose a democratically elected leader.

Ramsey said what's happening now is unprecedented.

"I have never seen a caucus so lacking in discipline as these dissenters seem to be right now," he said.

Ramsey said if they can't work with James they should leave the NDP caucus and sit as independents.

Corky Evans also writes letter

But other NDP stalwarts disagree.

One of Ramsey's former cabinet colleagues, Corky Evans, has released an open letter of his own.

He blames James for orchestrating the divisions by outing the dissidents at a party meeting last month.

Jenny Kwan's highly critical challenge of Carole James's leadership has prompted the Sunday showdown. CBC"As a New Democrat, I am heartsick at the troubles and I fervently wish [James] had not orchestrated the public division of her caucus," Evans said.

Ramsey said Kwan should know better.

"We sat in caucus, Jenny and I, when our public opinion approval rating was at less than 20 per cent," Ramsay said. "And we did not break ranks, we did not take out after our leader, we did not call upon the party to split and turf out a leader without proper democratic processes."

The pivotal NDP meeting takes place at 4 p.m. PT Sunday.

With files from the CBC's Jeff Davies