TORONTO -- Ontario's health minister resigned abruptly Monday, making him the fourth high-profile Liberal to step down just months ahead of a provincial election.

Eric Hoskins, who has been a member of provincial parliament for eight years, said in a statement his resignation as minister and a Liberal legislator representing a Toronto riding is effective immediately.

Hoskins gave no reason for his departure, but said he will continue to work on building the health-care system for all Canadians. A source said Hoskins is leaving for a senior federal position related to health care.

While Hoskins was health minister, the Liberals introduced a pharmacare plan that covers 4,400 medications for people under 25. The plan, which was a key plank of last year's provincial budget, took effect in January.

Ontario Premier Kathleen Wynne thanked Hoskins for his work and announced that Helena Jaczek will take over as Ontario's health minister. Michael Coteau will take over Jazcek's former role of Minister of Community and Social Services and maintain his role as Minister of Children and Youth Services.

The move comes roughly a month after Wynne shuffled several senior portfolios in her cabinet to prepare for the departure of three ministers who announced they would not run in the June election.

Mitzie Hunter, who previously served as education minister, took over the advanced education portfolio from Deb Matthews.

Eleanor McMahon, the former minister of tourism, culture and sport, replaced Liz Sandals as Treasury Board president. And Steven Del Duca, who previously served as transportation minister, stepped in as minister of economic development, a post left vacant by Brad Duguid.

Matthews, Sandals and Duguid have since been appointed as parliamentary assistants to the premier or various ministers.

Many of the ministers involved in the shuffle represented ridings in the Greater Toronto Area, which will be a key battleground in the election.