TORONTO (Reuters) - Canada's ruling Conservatives held on to two House of Commons seats in special elections on Monday despite a strong challenge from the opposition Liberal Party, led by former prime minister Pierre Trudeau's son Justin.
The Liberals moved ahead to second place in both districts, after dismal showings in the 2011 general election. The results helped solidify their role as the main rivals to Prime Minister Stephen Harper's Conservative Party in next October's general election.
The Liberals came closest to taking an Ontario seat last held by late Conservative Finance Minister Jim Flaherty. Preliminary results showed them winning 41.3 percent of the vote, compared to 48.7 percent for the Conservatives.
The Liberals, who governed Canada for the majority of its history, have been making a comeback from their worst electoral showing ever in 2011. Most recent polls have shown them ahead of the Conservatives nationally.
They had come in third behind Flaherty and the candidate of the New Democratic Party in the Ontario district of Whitby-Oshawa in the 2011 election.
In the other electoral race on Monday to fill a vacant seat in a Conservative bastion in Alberta, the Liberals vaulted from fourth place to second.
The New Democrats became the official opposition in 2011, meaning they hold the second highest number of seats in the House. But they have struggled since former leader Jack Layton died just months after the election.
Trudeau has urged more infrastructure spending and opposed Canada's military involvement against Islamic State fighters in Iraq. Harper has just introduced new family tax cuts and benefits, and has emphasized the importance of balanced budgets.
Reporting by Jeffrey Hodgson, with additional reporting by Randall Palmer in Ottawa; Editing by Nick Macfie