Monte McNaughton says he has decided to run to replace former PC Leader Tim Hudak, who resigned after losing his second consecutive election to the Liberals in June.
The 37-year-old McNaughton has already visited 54 of Ontario's 107 ridings seeking support from Conservatives in advance of a leadership convention that's not expected until sometime next year.
McNaughton says the Tories must get rid of the insiders responsible for what he calls disastrous election campaigns, and wants all party members to have a vote on their next election platform.
He is only the second declared leadership candidate after Whitby's Christine Elliott, deputy PC leader and widow of former finance minister Jim Flaherty.
But two other Ontario Tories, Vic Fedeli and Lisa MacLeod, have been signing up caucus colleagues to support their leadership bids, which aren't expected to become official until next week.
Federal Conservative MP Patrick Brown has also been signing up new members and supporters for an expected run for the Ontario PC leadership.
McNaughton was first elected in 2011 in the Sarnia-area riding of Lambton-Kent-Middlesex, after a failed attempt in the 2007 election, and has held a number of shadow cabinet posts including labour critic.
Before entering politics, McNaughton was general manager and co-owner of the McNaughton Family Shopping Centre in Newbury, and was president of the Strathroy and District Chamber of Commerce in 2009-10. He graduated from Westervelt Business College and successfully completed executive programs at the Richard Ivey School of Business.
McNaughton said the party has fallen to just 10,000 members from a high of 100,000 a decade ago, and he has a plan to rebuild it with a coalition of new Canadians, young families, post-secondary students and blue collar workers.
"We need these groups quite frankly in order to win government, and as a party we need to do a better job of representing all of Ontario," McNaughton said in an interview.
"My thinking is we're never going to win an election getting 30 to 35 per cent of the vote, and we need to expand the Conservative Coalition."
McNaughton plans to visit all 107 ridings by early next month to get feedback from Conservatives all across Ontario on the party's future.
"We need to change the culture in the party and flip the organizational chart upside down and put party members and voters at the top and the party leadership at the bottom," he said.
"The party leader is there to serve the members, but in the last decade or so it's become apparent it's really the other way around."
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