Brian Topp, Premier Rachel Notley's chief of staff, is leaving his position in the biggest shakeup to the Alberta NDP since the party won the election 18 months ago.

Topp, a former party president of the federal NDP who ran for the NDP leadership in 2012, finishing second to Tom Mulcair, joined the Notley government in May 2015.

Notley thanked Topp in a news release Wednesday.

"He was instrumental in advancing such major initiatives as the climate leadership plan, establishing a stable electricity market and securing approval for the Trans Mountain Pipeline," she said.

Topp also ran the Alberta NDP "war room" during the campaign.

Topp is returning to Ontario where he has been named senior fellow at Canada's Public Policy Forum, an Ottawa-based think tank.

Notley is replacing Topp with John Heaney.

Heaney, who grew up in Edmonton and once worked for the Alberta NDP caucus in the 1980s, most recently served as the Alberta government's deputy minister of policy co-ordination.

"John is enormously qualified, with decades of experience working in senior government and legislative positions," Notley said.

Notley also named Jim Rutkowski, who was Finance Minister Joe Ceci's chief of staff, as principal secretary in the premier's office, while current principal secretary Anne McGrath moves to Calgary to lead the premier's southern Alberta office as executive director, replacing Bob Hawkesworth.

Hawkesworth, a former NDP MLA who was appointed to the position after losing a byelection, is "moving on from government" next week.