Nigel Wright, former chief of staff to Prime Minister Stephen Harper, leaves the Ontario Court of Justice in Ottawa August 12, 2015. A former top aide to Harper could reveal potentially damaging details about a corruption scandal as he takes the stand on Wednesday at a trial that threatens to eclipse the ruling Conservative's re-election bid. Wright, is the highest-profile witness to testify in the months-long trial of Conservative Senator Mike Duffy, who is accused of receiving a bribe and abusing expense claims two years ago. REUTERS/Blair Gable