The article referenced in the above tweet includes:
Fresh off the chief electoral presses comes word that the already hotly contested riding of Toronto Centre is now officially up for grabs, which, with the previously announced vacancies in Bourassa and Provencher, brings the total number of Commons seats currently in need of filling to 3.
Under the Elections Act, the PM — well, technically, the Governor General, but let’s not overcomplicate this –must issue a writ no later than 180 days after an official notice of vacancy is received by the Chief Electoral Officer.
Toronto Centre Debates - All candidates debate 