Jagmeet Singh, the deputy leader of the Ontario NDP, will seek the leadership of the federal New Democrats, CBC News has learned.

Multiple sources close to Singh said he will officially announce his candidacy at an event next Monday evening in Brampton, Ont., with the promise of a campaign launch unlike any in the NDP leadership race so far.

Singh, a 38-year-old lawyer who speaks French and Punjabi, has represented the riding of Bramalea-Gore-Malton in the provincial legislature since 2011. He has served as the Ontario NDP's critic for justice and consumer services, and party leader Andrea Horwath named him her deputy in 2015.

He will become the fifth official candidate in the race to replace Tom Mulcair as federal NDP leader. MPs Peter Julian of B.C., Charlie Angus from northern Ontario, Guy Caron of Quebec, and Niki Ashton of Manitoba were the first four entrants.

Some observers predict Singh will inject some excitement to the race, but warn that he faces significant challenges in winning a national campaign.

"He really has that kind of charisma that people enjoy," said Kathleen Monk, former director of strategic communications for Jack Layton.

"He brings a lot of new blood into the race, he will represent a lot of urban, youth-focused issues," Monk said in an interview with CBC News. "I think if I was a Liberal, I wouldn't want to be running against Jagmeet."

For Singh to succeed, he must prove he has support across the country, Monk said.

As speculation swirled in recent months about whether Singh would seek the leadership, he has been increasing his national profile.

<a href="https://twitter.com/theJagmeetSingh">@theJagmeetSingh</a> joined me and campaign volunteers in Surrey Whalley to get the word out about <a href="https://twitter.com/hashtag/bcndp?src=hash">#bcndp</a> plan for a <a href="https://twitter.com/hashtag/BetterBC?src=hash">#BetterBC</a> <a href="https://t.co/wVfDzhB3M3">pic.twitter.com/wVfDzhB3M3</a> —@BruceRalston

Proud to have the support of brother <a href="https://twitter.com/theJagmeetSingh">@theJagmeetSingh</a> on my leadership campaign. Great day charting new directions for New Democrats <a href="https://twitter.com/hashtag/vibes?src=hash">#vibes</a> <a href="https://t.co/7CasiUMYQW">pic.twitter.com/7CasiUMYQW</a> —@WabKinew

Karl Bélanger, the NDP's former national director, agrees that Singh has charisma and finds it interesting that he's choosing to launch his campaign in his riding.

"Having a big launch is important. But if you do it in your own backyard, it doesn't really signal much in terms of growth potential," said Bélanger. "Montreal, Vancouver or even downtown Toronto would send a stronger message."

"I think his main weakness is not being known," said Peter Graefe, a political scientist at McMaster University in Hamilton. "He's known by political watchers in Ontario, but probably not by the greater public. He's not that well-known in the other provinces."

"One of his strengths is his populist ability to speak to working-class Canadians in a way that NDP leaders have had a hard time doing," said Graefe in an interview.

Singh "will have to address the race issue among some constituencies," said Monk.

"He represents the views of many racialized Canadians. I think that's really important. I wouldn't underestimate that value of having him run and what kind of momentum he can build on that," she said. "If elected as leader, he will be the first leader of a major party that is Sikh. A turban-wearing man is not insignificant for Canada."

Next leadership debate: May 28

Two others, former veterans ombudsman Pat Stogran and Montrealer Ibrahim Bruno El-Khoury, have registered with Elections Canada as NDP leadership contestants, but their candidacies are not yet considered official by the party. Official candidates must pay a $30,000 fee and submit a list of 500 signatures that meet diversity and regional requirements.

Singh will join the race in time to participate in the NDP's third leadership debate, on May 28 in Sudbury, Ont.

NDP members will commence voting on Sept. 18, with successive ballots to follow weekly throughout October until one candidate gets 50 per cent of the vote.

Singh's first run for politics was in the 2011 federal election. He came within a few hundred votes of winning Bramalea-Gore-Malton, then five months later won the seat in the provincial election.