The leadership review is automatic, held every second year, but there are many New Democrats still fuming over Horwath's campaign strategy and wondering why she triggered the election by defeating a very NDP-friendly Liberal budget.
Horwath said she's listened to critics who accused her of abandoning core NDP ideals by rejecting the May 1 budget with its call for a new provincial pension plan, more spending on public transit and an increased minimum wage.
"I've worked really hard to reach out to our party members who saw some concerns with the campaign," she said in an interview. "Our campaign had some victories and it had some failings, and we've learned from both of those things."
In the midst of the election, 34 prominent New Democrats signed a letter accusing Horwath of sacrificing progressive values and "running to the right of the Liberals" in an attempt to win votes.
And while there are no open challengers to her leadership, two veteran members of her caucus, Peter Tabuns and Cheri DiNovo, had publicly criticized the way the NDP election campaign was conducted.
But other caucus members, including Brampton's Jagmeet Singh, predicted that Horwath would still be NDP leader following Saturday's vote, despite complaints from some delegates about her campaign efforts.
"I'm very confident that she's going to survive the vote, and I think that people grumbling and having concerns is part of democracy," said Singh. "We're looking forward to hearing those concerns because we can grow from those."
The NDP's socialist caucus circulated a petition saying Horwath had no mandate to "wage a right-populist campaign that alienated labour unionists, social justice advocates and progressives," and therefore must step down.
Other New Democrats who didn't want to be named said there was a lot of anger at Horwath over the campaign among the more than 1,000 delegates registered to the convention, and not just among the socialist caucus.
Horwath downplayed the internal dissent, and said she made changes in leadership in her office following the campaign, and insisted the party would emerge from the convention united and focused on the future.
"This convention is about the work I did over the last couple of months, the changes I've made to my team, the pulling in of some of those folks and getting their feedback in terms of their concerns about the campaign," she said. "We are certainly going to work together as a party to fashion our next campaign, and we have four years to do that building."
The NDP lost three Toronto seats in the election but picked up three others in Oshawa, Windsor and Sudbury to return with 21 MPPs, compared with 58 for the Liberals and 28 for the Progressive Conservatives.
The June 12 loss also wiped out the balance of power the NDP had held since the 2011 election when the Liberals had been reduced to a minority government.
Liberal Arthur Potts, who took the riding of Beaches-East York from veteran New Democrat Michael Prue in June, said Horwath campaigned as a socialist in 2011 and then went so far right she chased Conservative votes in this year's campaign.
"It just isn't clear what she stands for, and those around her don't seem to know either," said Potts. "It's no wonder that long time party activists and NDP members have publicly questioned her leadership."
Horwath will have one last chance to address the NDP delegates Saturday morning before the leadership vote.
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