There's trouble in paradise for the Liberal Party of Ontario as they head into their leadership convention on Saturday.

The unions are rallying against them.

Yep, the Ontario Federation of Labour -- including many unions that had previously been the Grits' BFFs -- are now threatening a massive demonstration as the Libs congregate in their leadership bunfight.

The OFL has pulled together 90 disparate groups -- from Occupy Toronto to the Ontario English Catholic Teachers Association (OECTA) -- under the "We are Ontario," and "Ontario Common Front," banner.

OFL President Sid Ryan says labour has been galvanized by the government's fight with the teachers.

"Given Bill 115, I think there will be a lot less union support for the Liberals. I think you will find a lot more support for the NDP from the OFL," said Ryan, who's run as a New Demcocrat five times.

This marks a sharp change in direction for some unions, who in the past have donated money and workers to Liberal campaigns.

Ryan said his group is not associated with the Working Families Coalition (WFC), a group that's come together for the past three elections to buy massive TV advertising campaigns to slam the Tories -- from Ernie Eves, through John Tory and on to Tim Hudak.

Ryan says the OFL spent the last 18 months building this coalition.

"We realized Ontario was falling behind and in nine out of 10 categories, this province is dead last," he said, citing issues such as post-secondary education, healthcare funding and poverty.

The OFL is spending about $50,000 on this campaign.

Meanwhile, PC leader Tim Hudak and the NDP's Andrea Horwath are eyeing the Liberal convention warily.

They can't vote for the next premier, but who'd they rather run against in the next election?

For Hudak, the high probability of the next premier being a woman is a double-edged sword.

On one hand, does he really want to be the lone guy on the stage debating two women?

On the other, it makes it easier to define himself if he's the only man.

You can't help thinking he'd prefer someone on the left of the party -- such as Kathleen Wynne or Gerard Kennedy.

Sandra Pupatello is to the right. Her previous ministerial experience has been in economic development -- a business role that Hudak's trying to establish himself in.
Wynne, on the other hand, is more lefty, touchy-feely.

She's the person most likely to kiss and make up with the teacher unions -- and that could hurt Horwath and the NDP.

Ditto for Kennedy. Throughout the campaign, he's positioned himself as a friend of the unions and someone who can get along with them -- a teacher's pet, if you will.

Is the bad blood between the Liberals and the unions there for good?

If either Kennedy or Wynne become premier, would they cut a deal with the unions?

That would be good news for Hudak, bad for Horwath.

Another key question is who will those nasty WFC ads target in the next election?

Will they stick with the tried and true -- and attack the Tories? Or will they take a double-pronged approach and also attack the new Liberal leader?

If they don't go after the Grits after their massive fight over Bill 115, WFC will appear hypocrites.

It all adds up to massive labour pains for the Liberals.

It looks good on them after they spent nine years caving in to every union demand.

Now the unions will be out on the street -- carrying placards -- at the convention.

Will the new premier bring them in from the cold?