The Welsh Conservatives say the Swansea Tidal Lagoon should go ahead despite indications the UK Government may be about to turn it down.
UK Ministers are expected to make an announcement about it's future within the next few days.
They have repeatedly said it has to demonstrate 'value for money' but the Welsh Conservatives have dismissed that argument as 'a red herring'.
South Wales West am, Suzy Davies, says it would be the 'most regenerative scheme in Wales' since the development of Cardiff Bay.
The project was backed by an independent review but has not yet been approved.
Earleir this Month, Welsh Secretary, Alun Cairns MP, came under fire in the monthly Wales questions session in the House of Commons about the continued silence over the multi-million pound project.
Mr Cairns said as much he would like the tidal lagoon to go ahead, it must 'deliver value for money for the taxpayer'.
First Minister, Carwyn Jones, offered £200m of Welsh Government investment towards the project but the Welsh Secretary said it was 'a fraction of the cost of the lagoon.'
He said the Hinckley deal was the 'most expensive' they'd accept, and that currently, the Tidal Lagoon was 'twice cost of nuclear.'
The UK Government have been asked to comment.