Ontario MPP and Progressive Conservative leadership candidate Patrick Brown appealed directly to his grassroots supporters at a campaign event Sunday, saying abandoning his platform could destroy the party.

"We can't win by walking away from the platform that our party members worked so hard to build," said Brown, referring to the People's Guarantee, which the PCs rolled out last November.

Speaking to a room of supporters at a Mississauga, Ont., hotel, Brown also addressed the four other candidates running to take the PCs into the June 7 provincial election as leader.

"You can turn your back on me but you can't turn your back on the members," he said, mentioning Christine Elliott, Caroline Mulroney, Doug Ford and Tanya Granic Allen by name.

Brown, who was joined on stage by more than a dozen PC candidates, as well as several sitting MPPs and one MP, also warned that changing directions so close to election day will translate into another defeat for the party.

"You cannot make policy on the fly this close to an election," he said. "It is a recipe for disaster."

The former Ontario PC leader registered to run in the party's snap leadership race on Friday, hours before the deadline to enter the contest expired. That move came shortly after PC interim leader Vic Fedeli announced that Brown, who represents Simcoe North, had been booted from caucus.

The scene as Patrick Brown enters <a href="https://t.co/bKxr9VfUwv">pic.twitter.com/bKxr9VfUwv</a> —@CBCLorenda

His unexpected candidacy has further roiled a party already reeling from the fallout from Brown's resignation as leader last month following allegations of sexual misconduct levied by two women and first reported by CTV.

At his rally on Sunday, Brown asserted multiple times that he has "cleared his name" and that he has received support from people "at gas stations and coffee shops" who encouraged him to jump back into the fray.

"What has happened to me, I wouldn't wish on my worst enemy. To be vilified without due process is absolutely gutting," he said.

"To be shunned as an outcast from the party that I love over fabricated news reports — it hit me like a ton of bricks."

Last week, Brown took direct aim at the women's claims, as well the original CTV report, in lengthy statements posted to social media in which he denied the allegations.

Brown's entry into the leadership race was met with sharp criticisms from the other candidates.

On Sunday, PC MPP Randy Hillier issued a statement reiterating his position that Brown is "unfit to be in the Progressive Conservative caucus, he is unfit to be the leader of [the] PC Party and he is unfit to be premier."

Speaking to reporters after his speech, Brown said that when he took over as leader, the party was in debt and frequently "getting embarrassed in byelections." He repeated his team's assertion that, under Brown, party membership swelled from some 12,000 to more than 200,000 members.

Fedeli, however, said in an email to the Tory caucus earlier this month that the party has roughly 67,000 fewer members than the 200,000 Brown claimed in early January.

Brown said the specific numbers aren't what matters.

"Whether it's 145,000 or 180,000 or 200,000, it's still the largest we have ever been. Members expire every month, so the number does change," he told the crowd.

Hannah Sadovnick, 22, said she attended Sunday's rally because she's been a staunch supporter of Brown since she heard him speak at an event at Ryerson University last year.

"Patrick inspired me," she said. "He has so many policies that relate to people my age. He's going to cut back on income taxes, he cares about mental health, he cares about families."

Sadovnick said she doesn't believe the misconduct allegations.

"As soon as I (saw) it I rolled my eyes," she said, adding that she has signed a petition in support of Brown against his accusers. "I'll stand by him the whole way through."