A former St. John's MP says Liberal leadership candidate Justin Trudeau will flourish because of his appeal among younger voters.

Trudeau, who formally announced to his campaign to lead the Liberal Party of Canada on Tuesday night, also has strong credentials for national unity, says Siobhan Coady, who represented St. John's South-Mount Pearl until she was defeated in last year's election.

Coady, who is campaigning for Trudeau, 40, said the youth vote will be critical in the leadership contest that concludes in April.

"If you look at Justin's appeal, it tends to be to the younger people who really look forward to a different version of Canada, to an improved version of Canada, and I think that's what Justin brings," Coady told CBC News.

Coady acknowledged that Trudeau's name is both a blessing and a curse, and presents a challenge that to appeal to voters who might see him as trading on the family name, or former opponents of his father, Pierre Trudeau, who served as prime minister in different governments between 1968 and 1984.

"In some ways, he has to overcome some of the legacy, but I think Mr. Trudeau — Justin Trudeau — is looking forward to the future here," Coady said.

"He's really engaging a lot of youth who would not recall, intimately, that Pierre Trudeau, his father, was the prime minister."

Coady said she supports Trudeau in part because of his intelligence and charisma.

Trudeau has emerged as the early frontrunner in the Liberal leadership race.

Among his opponents is Deborah Coyne, who was a constitutional advisor in the early 1990s to former Newfoundland and Labrador premier Clyde Wells … and who is the mother of Justin Trudeau's half-sister.

Coady said the family dynamic between Trudeau and Coyne may be interesting, but she's more interested in their policy views.

"They both have a family connection, but I think … both are looking for the best version of Canada [and] a better version of Canada than we have now."