TORONTO – A former parliamentary secretary who used to speak for then-prime minister Stephen Harper against election-fraud allegations levelled at the Conservatives lost his bid Thursday to have the country’s highest court weigh in on his own convictions for electoral fraud.The decision by the Supreme Court of Canada not to hear his appeal means that Dean Del Mastro, initially convicted in 2014 for offences committed a decade ago, has reached the end of the road in his efforts at exoneration.“It seems like a modest word at times like these, but I’m obviously terribly disappointed,” the former Conservative MP from Peterborough, Ont., told The Canadian Press. “I had hoped to be able to fight for a just outcome through the courts, but it’s not to be.”Del Mastro said he now planned to sue Elections Canada for what he called the “negligent” investigation that led to his convictions. He said he would be seeking unspecified damages.“We’ll go after them and call into question aspects of this investigation which were negligent, which led to an outcome which is not just,” Del Mastro said. “My campaign followed all the rules.”Ontario court Judge Lisa Cameron convicted Del Mastro, 47, of three electoral offences related to his 2008 re-election campaign: overspending, failing to report a $21,000 contribution he made to his own campaign and knowingly filing a false report.Cameron handed him a one-month jail term along with four months house arrest and 18 months probation for what she called his “cheating and lying” in his “affront” to democracy. The judge also ordered him to pay $10,000 in restitution.“He was prepared not only to break the rules but to be deceitful about it,” Cameron said at the time.Del Mastro, once a staunch and vocal defender of Conservative policies, appealed but lost at the Superior Court and Appeal Court levels.In April 2016, Superior Court Justice Bryan Shaughnessy upheld both the convictions and sentence — while setting aside the restitution order. In September, the Ontario Court of Appeal upheld the convictions.“The offences were serious and struck at the heart of the democratic electoral process,” the court said.Del Mastro, granted bail at various points while his appeals wound through the courts, won’t now have to go back to jail despite his latest legal setback. He had already been granted statutory release after serving 20 days in jail.However, he will now have to serve the four-month conditional sentence from his 83-hectare farm in Bailieboro, south of Peterborough, although he said he would be allowed to travel to his energy-development work a couple of times a week.“I guess it’s more like farm arrest in this case,” Del Mastro said. “I wanted to start immediately, so I have.”After his conviction, which also precluded his running for Parliament for five years, the disgraced politician resigned the Peterborough seat he had won three times.Del Mastro, who has steadfastly maintained his innocence, remained defiant on Thursday, insisting the voters were short-changed by what happened to him and refused to rule out another run for political office at some point.“If I can’t get justice and a just outcome from the courts, then maybe I should seek it from the voters,” Del Mastro said. “The most fundamental right of citizenship is people’s democratic franchise, and that’s what was crushed and taken away and that’s why the Supreme Court should have heard the case.”Del Mastro’s elections agent, accountant Richard McCarthy, 68, was given a two-month conditional sentence plus one year of probation for his role.