Plaid Cymru's Adam Price will outline his vision of an independent Wales by 2030 as he formally launches his leadership campaign in Carmarthen. Since announcing his intention to challenge Leanne Wood, Mr Price has called for the party to change its name to New Wales to broaden its appeal.
The Carmarthen East and Dinefwr AM has also called for a 1p increase in income tax to boost education. Rhun ap Iorwerth is also challenging Ms Wood in a three-way contest.
Mr Price has said he wants to establish Plaid Cymru as "the natural party of government" in Wales, following the example of the SNP which has been in power in Scotland since 2007. But he has claimed Plaid Cymru is "at a crossroads" and faces defeat if it does not change direction.
The former MP's goal is to win the next two Welsh Assembly elections - in 2021 and 2026 - and follow them with a referendum on independence, which he claimed "we will fight and win".
Speaking ahead of the launch, Mr Price said: "Independence is the reason I joined Plaid Cymru and the reason I have remained a member for 36 years.