Termination Due To Non Performance

Hello everyone,
i m working as HR head in a readymade garment industry having approx. 900-1000 employees.
I want to sack few employees from one of the department as they are not performing and even they are involved in provoking other employees to unnecessarily create problem and unionism.
Have many times warned them to improve their performancebut no result.
Generally after 3 warning letter & show cause notice we can terminate an employee but here the matter is the person has good relaion with the labor leader & the leading politician in town and so issuing show cause notice can create problem.
require your suggestion

dear
you have to take action against them.termination even after warning letter and show cause will not hold good in law.
just make a target list and catch one by one.i you have to follow complete process like charge sheet,domestic enquiry and if need arises suspension also.
even you can terminate directly but again it will be illegal and will create problem in court of law.discuss your startegy with top management.
tks
js malik