Guernsey's Public Services minister has warned delays to the runway project may cost the island millions of pounds.
Next week the States is due to debate whether to approve the compulsory purchase of a field needed for the work to go ahead at Guernsey Airport.
Two deputies believe the project does not comply with planning laws and want a delay to allow it to be investigated.
Deputy Bernard Flouquet said if they succeeded the current project would no longer be possible.
He said it was unthinkable that his department had not consulted the island's planning authorities before progressing the project.
Deputy Flouquet said: "Why would Public Services expend the public purse in excess of a million [pounds] purely and simply to find out at this particular stage that there is no policy there for us to make this submission?"
The £81m project, which involves the reconstruction of the runway and other hard surfaces, creating longer safety areas and the replacement or refurbishment of the drainage system, airfield lighting and other key operational systems, was agreed by the States in 2009.
Deputy Flouquet said: "We cannot say for sure how long any delay would set us back, but it would be several months.
"It will mean having to spend more money patching the existing runway in the hope that it does not disintegrate further in the meantime and require more expensive repairs.
"There will also, I suggest be the significant additional cost of redesign and potentially a new tender process."