Brian Gallant will officially launch his bid for the Liberal leadership on Wednesday.
Gallant is a former president of the student union at the University of Moncton.
He challenged then-premier Bernard Lord for the riding of Moncton-East in 2006 but lost.
Gallant did not run in the last provincial election.
So far, former health minister Mike Murphy and Belledune Mayor Nick Duivenvoorden (Dy-ven-vor-den) are the only other declared candidates.
The Liberals will choose their new leader in October.