A relentless crackdown widely attributed to Pakistan's powerful military has seen Imran Khan and his Pakistan Tehreek-e-Insaf (PTI) party almost erased from the election campaign ahead of the vote. "Our party workers are facing harassment, and I personally have received death threats," says 61-year-old Jamal Ahsan Khan, who is standing for PTI in Mianwali in place of his leader.