Toronto MPP George Smitherman resigned from his post at the Ontario legislature in a first step towards his bid to run for city mayor.

The former cabinet minister had previously announced he would be leaving Queen's Park to take a shot at Toronto city council. He faxed his resignation letter to Premier Dalton McGuinty on Sunday while on holiday. His departure takes effect immediately.

Though nominations for city council opened Monday morning across the Greater Toronto Area, Smitherman has yet to file his candidacy. Candidates have up until September to register.

After much speculation, Smitherman confirmed late last year that he would indeed run in the October municipal election to replace Toronto Mayor David Miller.

Several notable political hopefuls are expected to join the race.

Among them are former Liberal party national director Rocco Rossi and long-time councillor Giorgio Mammoliti -- all of whom are running to replace Toronto Mayor David Miller.

Political observers will watch closely to see whether former Ontario PC leader John Tory will throw his hat in the ring.

Tory's first venture into politics was in 2003 when he ran for mayor against Miller. He came in second.

Rossi was first in line to file his nomination papers. He told reporters afterwards that he pledges to cut his salary by 10 per cent if he's elected. He would then freeze that wage for his four-year term. The move will help prompt "adult conversation" with staff about cutting costs, he said.

The race for the mayor's chair in Vaughan could also get heated.

Current Mayor Linda Jackson has faced her fair share of scandals during her first term. However, she has said in the past she will run again to keep her job.

Jackson's former rival Michael Di Biase -- who served as Vaughan's mayor for one term in 2003 before Jackson beat him by a mere 90 votes -- has not said whether he will run again.

In Mississauga, 88-year-old Hazel McCallion is expected to run for mayor again -- a position she has held since 1978.

In Toronto, school trustee Josh Matlow ended speculation about his political future. He filed nomination papers to replace Coun. Michael Walker in the St. Paul's ward.

Walker has represented the area since 1982. Though he has not made an official announcement, it is widely believed the long-time councillor will retire from politics this year.

Monday marks the first official day candidates are allowed to campaign. The campaign will last until Election Day on Oct. 25.