Bob Rae is leaving  politics.

The former interim Liberal leader and one-time NDP premier of Ontario is stepping down as an MP, wrapping up a political career stretching  over 35 years and two parties.

Rae is leaving in order to focus on his new role as  chief negotiator for First Nations people  in talks with the province about development of the ” Ring of Fire”  mining development in northern Ontario.

Rae began in politics as a New Democrat and later shifted to the federal Liberals and sought the party leadership at one point.

He was first elected to the Commons in a 1978 byelection, but moved to Ontario provincial politics four years later, when he became provincial NDP leader.

He was premier from 1990-95 during troubled economic times and left a controversial legacy.

In 2006, having joined the Liberals, he unsuccessfully sought the party leadership, but won a seat in the Commons in 2008, becoming interim leader after Michael Ignatieff lost his seat in the 2011 election.

Rae says his decision has been a difficult one and quite emotional.