Prime Minister Stephen Harper has called a by-election for Monday, March 12 in the riding of Toronto-Danforth to fill the seat left vacant since the death of former NDP leader Jack Layton.

The announcement came first as a tweet from Andrew MacDougall, the associate director of communications in the Office of the Prime Minister. He said a news release would be issued soon. It appeared within a hour but only repeated MacDougall's tweet.

The NDP leadership convention will be held in Toronto on March 24. Speculation began at once in the Twittersphere that Brian Topp, a leadership candidate without a seat, would use the by-election as a way to get into Parliament. But Topp quickly wished candidate Craig Scott good luck in the campaign. Scott himself, as of midmorning Sunday, had not yet tweeted about the announcement.

Crawford Kilian is a contributing editor of The Tyee.