Hadi Khamenei said the Guardian Council 's vetting of candidates threatens Iranian democracy .
Hadi Khamenei is the brother of Supreme Leader Ali Khamenei and an adviser in the administration of reformist former President Mohammad Khatami .
Hadi Khamenei , the brother of Supreme Leader Ali Khamenei and an adviser in the administration of reformist former President Mohammad Khatami , said the Guardian Council 's vetting of candidates threatens Iranian democracy .