The next 48 hours are critical to saving 1,200 Wrightbus workers' jobs, according to Unite.
Unite Regional Officer for Wrightbus, George Brash, warned that there was now a real urgency in regards to resolving the land issue, which is now the only barrier to the factory gates reopening.
"Unite has been informed by the administrators that negotiations for sale of the company has moved to a point of exclusivity with a single, prospective buyer," he said.
"The only issue outstanding now is that of the land ownership associated with the factory site.
"Twelve hundred workers' livelihoods, the living conditions of their families and the entire local economy now hang in the balance.
"We understand that we are in a situation where if the issue of the land is not resolved in the next twenty-four to forty-eight hours then the prospect of safeguarding their future will disappear.
"We will be seeking a direct meeting with Jeff Wright to demand he does the right thing and hand over the land so as to remove this final obstacle to a sale and the gates reopening.
"Today a delegation of workers will tour the offices of local political parties."
"We need more than warm words from our local political representatives - we need deeds. The workers will be demanding that all local political representatives come out publicly today and demand that Jeff Wright hand over the land.
"This is a fight for the future of the Ballymena economy - it is a fight we can win. Politicians now need to come off the sidelines and get behind this workforce to secure that future".
In a statement TUV leader Jim Allister said: "With things potentially moving towards a deal which will restore manufacturing at Wrightbus, it is imperative that the maximum number of jobs are secured.
"Towards this end it is essential that all parties strive to overcome any outstanding hurdles, be it the land or otherwise.
“The saving of the factory must not be lost over a squabble about the land. So, my message to all is ‘get it done.’”