The Rail, Maritime and Transport union today announced that its 9,000 members working on the tube will be urged to support industrial action amid fears for their safety following a series of incidents.
The RMT's general secretary, Bob Crow, said that drivers would be asked to reduce speeds as part of a campaign of industrial action which would bring "complete chaos" to tube services.
Mr Crow said: "This will clearly cause disruption to members of the travelling public, which we deeply regret, especially in the run-up to Christmas.
"But the messages we have received in recent days from members of the public indicate that the overwhelming majority of people share our concerns."
Ballot papers will be sent out next week, and the results will be known on November 17.
The union will have to give seven days' notice of any industrial action, meaning that strikes could begin on November 24.
Mr Crow said that tube workers would be asked to operate "strictly within safety rules" and, as part of any industrial action, could reduce train speeds by up to half.
Station staff would also be told to make sure that overcrowded stations were closed, the union said.
The RMT has been seeking assurances from LU over the level of inspections and other safety standards following weekend incidents at Hammersmith and Camden Town.
"The responses we have had from the employers have fallen woefully short of the decisive action we have called for to reverse the dangerous decline in safety standards," Mr Crow said.
The union has been called to a safety summit with LU next week, but Mr Crow said that he was not prepared to tolerate any compromise on the issue.
He said that there could be a "continuous go-slow" as part of the industrial action, and drivers could be told to reduce their speeds to just 20mph.
The RMT repeated its welcome for today's announcement that Network Rail was taking maintenance of the country's overground railways back in-house.
But Mr Crow continued: "Given that welcome announcement, it is clear that any justification for maintaining these crazy contracts has now completely evaporated.
"It is untenable that the same companies now being kicked out of maintenance contracts on the national railway network should be allowed to continue to profit from declining safety standards on the tube."
