"We're going to make this very, very interesting," he said of an election expected in the province next fall.
"When you vote NDP it feels really good," he told cheering supporters at a convention in St. John's. With news cameras rolling, he urged others across the province to reject the governing Progressive Conservatives and Opposition Liberals.
"Shake off the shackles of the same old, same old and do something that's going to make a difference around here."
Just over 1,600 New Democrats were eligible to vote.
McCurdy, 65, is well known across the province for his 21-year career as president of the Fish, Food and Allied Workers union.
He beat two other candidates, Labrador mine worker Mike Goosney and Chris Bruce, a local coffee shop manager.
Of 1,298 ballots cast, McCurdy took 889 votes while Goosney had 299 and Bruce finished with 110.
Lorraine Michael led the third-place party since 2006 to historic results, winning five seats in 2011. But she announced in January she was stepping down after an internal rift over her leadership saw two of her five members leave caucus 16 months ago.
Since then, the party has slid in popularity. Recent byelection results were dismal.
McCurdy says the NDP can rebuild in time to offer a credible alternative in the coming election.
He had earlier approached the stage for his convention speech to Bruce Springsteen's "The Rising," written in response to the 9-11 terror attacks.
"It's about doing everything possible to ensure no one in our society is left behind," McCurdy said of how the NDP is distinct from the three-term majority Tory government and the Liberals.
He said switching to a Liberal regime would swap government colours and little else.
McCurdy stressed that the Liberals supported the government's bid to cut the number of seats in the legislature to 40 from 48 to save money, a move that will diminish rural representation, he said.
McCurdy, Bruce and Goosney also took shots at government cost-cutting plans. The oil-dependent province faces a growing $916-million deficit thanks to lower crude prices.
Premier Paul Davis has said "everything is on the table" for spending cuts coming in the spring budget.
"If you're in a hole, a hatchet is a lousy tool," McCurdy said in his convention speech.
Bruce, 26, made wiping out union and corporate donations a key part of his campaign. He said both create conflicts of interest that put citizens at a disadvantage.
"There is no way we will ever win if we allow for unlimited corporate cash to keep flowing into our political system."
Goosney, 37, devoted most of his 30-minute speech allotment to showing photos of new NDP members he said he signed up.
"Stay tuned because here we come," he said of his party's renewed potential. "Forward, we go."
Party president Kathleen Connors said it's the beginning of a new chapter after the damaging caucus split in 2013. There are now more than 1,600 party members compared to about 800 last year.
"The members very clearly spoke," she said of McCurdy's win.
"We're not starting from scratch. We've got a strong, firm foundation and it proves that we can, with hard work and commitment, continue to grow."
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