Both ridings were won by the Conservatives in the 2011 election, leaving the party to defend them at a time when they trail the Liberals in national opinion polls. Mr. Harper had previously declined to include then-vacant Whitby-Oshawa in the last round of by-elections, which were held in June and saw the Liberals steal a seat from the NDP and give the Conservatives a scare in another.
Whitby-Oshawa is among the seats in the “905” region surrounding Toronto, a vote-rich pocket where Conservative breakthroughs in 2011 helped lift the party to its majority status. The region is expected to once again play a key role in determining who will form government in the next election, scheduled for 2015. By calling both ridings at once, the federal Conservative Party can choose to pour more money into the Whitby-Oshawa riding, which Mr. Harper visited last week. Federal parties are given spending limits based on the number of by-elections and the populations in the ridings, but don’t need to spend the money evenly across ridings.
The Conservatives could spend disproportionately more in the Ontario by-election than in Alberta, where they’re widely expected to easily hold the seat. Federal law gave Mr. Harper until Oct. 25 to call the by-election in the Ontario riding. The Conservatives recently nominated Whitby mayor Pat Perkins as its candidate, after a process that included complaints of party interference from one candidate. The party dismissed the complaint and said it followed the rules.