Plans for what would be the world’s first tidal power lagoon were thrown out by the UK government last year.
Tidal Power plc’s chief executive Mark Shorrock said the five-year planning consent awarded by the government in 2015 expires in June 2020 “unless material works have commenced”.
He said the company was trying to raise £1.2m to start work on land.
The company will not be able to start work in the sea because it has not got a marine licence from Natural Resources Wales (NRW).
But Mr Shorrock said work could get under way on land as terms had been agreed with the principal landowners, subject to a final sign-off.
When the plans were thrown out, the Conservative government said the project was not value for money.
Labour and Plaid Cymru have pledged to deliver the Swansea Bay tidal lagoon in their general election manifestos, while the Liberal Democrats and Green Party of England and Wales support new tidal power investment.
The Brexit Party said it supports the use of tidal power but had concerns over the cost of the project.
Mr Shorrock told the Local Democracy Reporting Service: “With the increased awareness of the climate emergency, the rationale to deliver lagoons is stronger than ever and that view is shared by the majority of political parties contesting the 2019 general election.
“However, we must first remove the cliff-edge from the Swansea Bay tidal lagoon’s planning permission.
“No amount of political will can resurrect this vital pathfinder project if the planning permission is allowed to lapse.”
A spokesman for the Swansea Bay City Region lagoon task force said: “We are anticipating an announcement about the tidal lagoon in the new year.”