the president has the veto power,using which he can veto legislative act forcing the lawmakers to assemble super majority of votes to override the veto,but that is for example in this US almost impassible.Presidential election take place on a fixed date and cannot be held any time earlier or later,in case of death of president or his inability to rule,there is the vice president who take over all duties and answerable to president only and are not members of the legislature.