Millwall chief executive Steve Kavanagh says the club may relocate if they are forced to sell land near their stadium.
A review is being carried out into Lewisham Council plans to use a compulsory purchase order (CPO) to buy land surrounding the Den in Bermondsey.
In January, the council abandoned the CPO plans, but Kavanagh said it remains a "serious threat" to the club.
He says one prospective Labour candidate for Mayor of Lewisham has told him they would bring back the CPO.
"We've written to all of the five Labour nomination candidates for mayor last week, we've had some of those replies and one of those has come back and said they would bring the CPO back in the event they were made mayor," Kavanagh told BBC Radio London.
"I was asked in the event the CPO went through would we not move, and I said we'd have to consider everything and that still is the case."
The council planned to sell the land to a developer, Renewal, who wanted to build houses and a sporting village.
But a review by Lord Dyson into the process behind the CPO plans started in April and is expected to be finished before the end of the year.
"It's not something we want to do, but at the end of the day we have to be secure in our surroundings, we have to have the commercial rights in our surroundings and the ability to manage the access and egress to this ground," Kavanagh said.
"If we haven't got that here because it's taken away from us, then we will explore our options.
"We haven't gone into any great detail, but people have approached us and our position is in the event this goes through, then we will look at those much more closely."