Minority government: The Conservative government has 127 of the 308 seats in the House of Commons. It had to rely on the support of at least one other party to stay in power.
The Liberals had 95 seats, the separatist Bloc Quebecois 48, the left-wing New Democrats 30, and the Green Party one.
Three seats are held by
independents and four are vacant.
To win a majority, 155 seats
The result: The only parties to have run Canada since 1867 are the Conservatives and the Liberals.
The leader whose party holds the most seats is expected to become prime minister.
Length of campaign: Campaigns must last at least 36 days.
Because of legal spending limits, Canadian campaigns are rarely longer than two months.
How soon do new governments move in?: If the Liberals win, they would typically take power two
If the Conservatives stay in power, a cabinet lineup would be expected in two or three weeks.
Parliament might convene in early December or late January.
Harper said: "They will choose between clear direction or uncertainty, between common sense or risky experiments, between steadiness or recklessness."
The Conservative party must win an additional 28 seats to gain a majority in parliament, and analysts say they have a better chance of doing so now rather than later.
Harper has said in recent weeks that elections are needed to deal with a possible recession.
Manufacturing sectors in the most populous provinces, Ontario and Quebec, are suffering due to the global economic slowdown.
Harper used the announcement on Sunday to tell opponents that criticism of his government "masks unclear and risky agendas".
"This government will continue to lead Canada by keeping taxes down and keeping the budget in surplus and limiting spending to clear and affordable objectives," he said.
Harper will press economic issues in his campaigning and oppose an energy tax proposed by the Liberal party.
Robert Bothwell, director of the international relations programme at the University of Toronto, said: "Harper is going for a majority government. That is really the only issue."
The government had enacted a law setting October 19, 2009, as the next election date.
The opposition parties say Harper is violating the spirit of the law by calling an election now.
Harper says an election is needed in order to provide a new mandate, since none of the opposition parties has confidence in his government.