The normally reserved Selinger, who is in his first campaign as party leader for the Oct. 4 provincial election, went on the offensive during the two-hour debate broadcast live on radio.
At one point, McFadyen said taxpayers must be protected in the NDP government's recent decision to build a $100-million emergency channel to reduce high water levels on Lake Manitoba and Lake St. Martin.
Selinger cut him off.
"Are you flip-flopping on that, just like everything else?" Selinger asked.
"We support the building of the channel. I don't know why...." McFadyen tried to continue.
"You've got to spend the money to build it. You can't have it both ways," Selinger interrupted again.
"Are you OK?" McFadyen asked.
"Are you OK? Are you OK?" Selinger fired back.
Selinger displayed a more aggressive tone throughout the debate.
He has long faced criticism for ordering Crown-owned Manitoba Hydro to reroute a planned transmission line called Bipole Three to the west of the province. The decision was made to protect the boreal forest in the east, but will add hundreds of kilometres to the line and at least several hundred million dollars to the price tag.
On Monday, he accused the Tories of threatening the entire project by letting Hydro revert to its original route, which could face opposition from environmentalists and aboriginal groups.
"Only the leader of the Opposition will derail it with his crazy plan to put the Bipole down the east side (of the province)," Selinger said.
The election will be the first test of Selinger's popularity. He was chosen by NDP delegates to take over the party leadership in 2009 following Gary Doer's decision to step down and become Canada's ambassador to the United States.
Selinger is trying to win a fourth consecutive mandate for the New Democrats. Opinion polls suggest the race is the closest the province has seen since 1999.
There were no knockout punches in the debate as the leaders stuck to positions they have taken since the campaign officially began last week.
McFadyen accused the NDP of misleading voters by running ads that accuse the Tories of having a secret plan to privatize Manitoba Hydro and other Crown corporations. It's a position McFadyen has repeatedly and consistently denied.
"The record is very clear. There has been a priority on privatization by my opponent," Selinger countered, referring to the former Tory government's sale of Manitoba Telephone System in 1997. At the time, McFadyen was chief of staff to then-premier Gary Filmon.
"I think (Selinger) is running a very dishonest campaign, and I think sometimes when people are desperate to cling to power, they're dishonest," McFadyen said.
Liberal Leader Jon Gerrard, the party's lone legislature member when the election was called, frequently found himself on the sidelines of the back-and-forth debate. He focused his efforts on the economy and the environment, and accused the government of not doing enough to keep young people from leaving for greener pastures.
"We've had consistent migration of Manitobans, a net loss inter-provincially of Manitobans. We should be doing much better here in Manitoba," Gerrard said.
— By Steve Lambert in Winnipeg