Partial mothballing has begun at the Redcar site
Union leaders have been meeting in London to discuss "orchestrated action" in the wake of the partial mothballing of the Redcar Corus plant.
The GMB, Community and Unite unions want to force the company to make a firm commitment to finding a buyer for Teesside Cast Products (TCP).
The blast furnace was shut down at the plant on 19 February, leaving 1,600 workers facing the axe.
Corus said it remained open to credible offers for TCP.
The site has been at risk since April 2009 when international buyers pulled out of a 10-year contract to buy steel slabs.
Terry Pye, Unite national officer, said: "The unions are meeting today to plan orchestrated and strategic action to put maximum pressure on Corus.
"Unite is ready to ballot its members for industrial action, if we get a yes vote we intend to be precise and effective.
"We believe that the company is failing to consider offers from its competitors to buy Redcar.
"With 10,000 jobs at stake in an area which has already been decimated by job losses, Corus has a moral responsibility to the workers and to the community.
"The workers have given years of loyalty and hard work and Corus owes them."
A Corus spokesman said: "Corus's position remains unchanged. This is a mothballing, not a permanent closure.
"TCP will be kept ready for a restart. Corus remains open to credible offers for TCP."