Bougainville's former president James Tanis is entering the contest to replace John Momis.
Bougainville is due to go regional elections in August after a delay caused by the Covid-19 crisis.
Mr Tanis, who was in power from 2008 to 2010, says he is one of the few political leaders still alive who was involved in negotiating the Peace Agreement 20 years ago.
He says there is a lot still to do after last year's resounding vote for independence from Papua New Guinea in Bougainville's non-binding referendum.
James Tanis said, as well as seeing through the ratification of the result there must be focus on what happens after, especially the process "to ensure that Bougainville is accepted by the current national and international community as an independent state."
"That is a road that is unmarked yet; that is yet to be negotiated. I think as someone who contributed to the Peace Agreement, I can contribute very well now," he said.
Mr Tanis said, as a central Bougainvillean, who was alongside both Francis Ona and Joseph Kabui, it is important to finally resolve the issue of the future of the Panguna copper mine.
The mine has been out of use for large scale mining for three decades since the start of the civil war.
While other politicians, including President Momis want to see the mine re-opened, Mr Tanis says before that happens outstanding issues needed to be sorted out, "The Panguna Mine will be an important project for the future of Bougainville, but we need to do things in a way that everybody is happy."
These are "the environmental issues, welfare issues, and possible re-opening issues," he said.