A Conservative MP desperate to hold on to his riding and a Liberal runner-up who went to court to get the razor-thin result overturned will make their cases to the Supreme Court of Canada this week.

The outcome of the case will determine whether Prime Minister Stephen Harper has to call a byelection in the Toronto riding of Etobicoke Centre.

Tory MP Ted Opitz won the riding by just 26 votes over Liberal Borys Wrzesnewskyj in last year's federal election. But Wrzesnewskyj went to court, claiming procedural irregularities.

Earlier this year, an Ontario Superior Court judge found that Elections Canada officials made clerical errors at the polls.

Justice Thomas Lederer threw out 79 votes and overturned the final result.

Opitz appealed the case to the Supreme Court, which will interrupt its summer break Tuesday to hear the case.

Only five other election results have been nullified by the courts since 1949. None of those rulings were appealed and byelections were quickly called to re-determine the will of the people in each riding.

The Etobicoke Centre result was overturned on the basis of improperly filled out paperwork for voters left off the list of electors or who needed someone to vouch for their identity.

In his ruling, Lederer specifically stressed the irregularities were the result of clerical errors by well-meaning Elections Canada officials, not the product of fraud or intentional wrongdoing.

However, since then, Wrzesnewskyj has resurrected other more serious allegations of ballot-box stuffing and voter suppression by Opitz's campaign, though nothing has been proven.

Until the top court resolves the case, Opitz is vowing to continue doing his job as MP for the riding. Wrzesnewskyj counters that Opitz should sit out votes in the House of Commons.

(The Canadian Press)