TORONTO - Ontario's Progressive Conservatives will choose a new leader June 27 despite opposition from some of its own caucus members, party president Ken Zeise said Sunday.

The party executive held firm to its initial decision to have a new leader before July 1 despite "intensive lobbying" from different groups over the past two weeks, he said.

That will give the Tories time to prepare for a fall legislative session that will "demonstrate that we are the alternative government in the 2011 election," Zeise said.

About half a dozen caucus members showed up Sunday to voice their support for a June convention, he added.

A few sitting Conservatives -- including veterans Elizabeth Witmer and Frank Klees -- wanted a longer race ending in a September convention.

Witmer, who has decided not to take another run at the leadership, said candidates need more time to build a platform and expand the party's base.

Klees, who is widely expected to make a bid himself, warned Friday that a shorter race would make it difficult for any sitting Conservative to juggle a province-wide campaign and their duties in the legislature.

The party's executive also set down the rules of the contest in Sunday's closed-door meeting, effectively firing the starting pistol in the race to succeed John Tory.

Tory, who had been without a seat in the legislature since the October 2007 provincial election, stepped down after losing a March 5 byelection in the rural riding of Haliburton-Kawartha Lakes Brock.

Candidates will only have until May 14 to sign up new members, which may scare off some outsiders and hobble a few leadership hopefuls currently sitting in the Opposition benches.

Caucus members Tim Hudak, Randy Hillier, and Christine Elliott -- who is married to federal Finance Minister Jim Flaherty -- are widely expected to run for the top job.

They'll also be expected to sit in the legislature during six of the next seven weeks when candidates can sign up new members.

Federal Human Resources Minister Diane Finley and Public Safety Minister Peter Van Loan -- a past president of the Ontario party -- are also rumoured to be testing the waters, as is Ontario Provincial Police Commissioner Julian Fantino.

But aides to both Finley and Van Loan have downplayed speculation that either minister is looking to jump into provincial politics.

Anyone who does take the plunge will have to dig deep: the party executive has set a $50,000 registration fee for candidates and they cannot spend more than $750,000 on their campaign.

The executive said it lowered the spending limit from $1 million set in the last leadership race in 2004 to reflect tougher economic times.

But money and time won't be the only factors that would-be contenders must consider: having a seat in the legislature may also prove to be a big advantage in the race.

Tory struggled for more than year to find a way back into the provincial legislature, which fuelled dissent over his ability to lead the party.

The party's rank-and-file would be "uncomfortable" with a leader who doesn't already have a seat, interim Leader Bob Runciman said Friday.

"You can't, I guess, close the door on that as a possibility," he said.

"But I think it would be a challenge for anyone to overcome those concerns within the party, given what's happened over the past year-and-a-half."

The party will vote for a new leader on June 21 and June 25, using ballots that will ask voters to rank the candidates in order of preference. Ballot boxes will be sealed and sent to the June 26-28 convention to be counted.

Already, there are signs that the leadership race may end up becoming an ideological battle for control of the party.

Much of the right-wing support seems to be swinging toward Hudak, who has reportedly received the blessing of former premier Mike Harris -- a hero to the party's most devout conservatives.

Hudak, the party's finance critic, served in Harris's cabinet and is married to his former chief of staff, Deb Hutton. He has remained tight lipped about his plans, but has hinted that any announcement would come after the March 26 budget.

Much of the rural vote -- a historic base of support for the provincial party -- might be siphoned off by outspoken rookie Randy Hillier if he throws his hat in the ring.

It's unclear who might win support from the party's more centrist "Red Tories," whose influence may be waning after Tory's unsuccessful run as leader.

Christine Elliott, who is married to federal Finance Minister Jim Flaherty, seems to be positioning herself as the candidate with the biggest tent.

A self-described "consensus builder," the lawyer and mother of triplet sons has spoken of the need to unite the party ahead of the next provincial election in 2011.

Both Tory and Runciman have said they will remain neutral in the race.