Stephen Harper's chief spokesman is leaving the Prime Minister's Office seven months before the official start of the next federal election campaign, a source said Friday.

Jason MacDonald, the prime minister's director of communications, took on the job in September 2013, after the previous spokesman, Andrew MacDougall, left. MacDonald had been the director of communications to Aboriginal Affairs Minister Bernard Valcourt.

Rob Nicol, vice-president of corporate affairs at Canadian Tire, will take over from MacDonald. MacDonald will join the public relations and lobbying firm Hill+Knowlton.

Stephen Harper's directors of communication

The average lifespan of a chief spokesman for the prime minister is about 18 months. Rob Nicol will be Harper's ninth director of communications since Harper became prime minister. The others were:

Jason MacDonald

Andrew MacDougall

Angelo Persichilli

​​Dimitri Soudas

John Williamson

Kory Teneycke

Sandra Buckler

William Stairs

Nicol has been at Canadian Tire in various roles since 2010, according to a resume posted online. He was also director of communications for Mike Harris when he was Ontario premier from 2000 to 2002.

Rob Nicol is taking over as director of communications to Prime Minister Stephen Harper as Jason MacDonald steps down. (Linkedin) ​While Nicol is leaving Canadian Tire for the Prime Minister's Office, another former PMO director of communications recently joined Canadian Tire. Sandra Buckler, who was Harper's spokeswoman for almost 2½ years, started with the company last month as vice-president of communications.

MacDonald is leaving the PMO in the wake of John Baird announcing his departure from federal politics. Baird, who was foreign affairs minister until he announced his plans to leave politics, has been a stalwart Harper supporter since the Conservatives formed government in 2006.

Harper has also cut ties with Dimitri Soudas, a long-time adviser and once director of communications, since Soudas was found to have interfered in the nomination race of his fiancée, MP Eve Adams, almost a year ago. Soudas was fired as executive director of the Conservative Party over the conflict. Earlier this week, Adams crossed the floor to the Liberal Party and said she had Soudas's support to make the move.