The overhaul of Atlantic Canada's only nuclear plant is almost two years behind schedule, and a former New Brunswick cabinet minister says the federal government is to blame.

Mike Murphy says the delay at the Point Lepreau nuclear plant is long enough to be considered a fundamental breach of contract.

The Moncton lawyer and leadership contender for the New Brunswick Liberal Party says the province should sue the federal government, and the federal agency in charge of refurbishing the plant.

Murphy also says the province isn't responsible for costs beyond the major project's original 18-month timeline, according to the terms of the contract.

Provincial Energy Minister Craig Leonard estimates the delay will cost roughly $2.4 billion.