A Canadian Forces veteran, who served for 27 years in such hot spots as Afghanistan, Bosnia and Kosovo, wants to take on veteran Conservative MP and former defence minister Peter MacKay in his Central Nova riding, setting up a tense dynamic for the 2015 general election.

David MacLeod is seeking the Liberal nomination in the northern Nova Scotia riding, which Mr. MacKay, now the Justice Minister, has represented since 1997.

"My name's David and he's my Goliath," Mr. MacLeod, 49, said in an interview Monday. He believes he can defeat the senior Stephen Harper minister with a campaign focusing on riding issues, such as job creation, but also on the plight of Canada's military veterans, many of whom believe they've been mistreated and betrayed by the Conservative government.

Story continues below advertisement

"Peter does know the defence portfolio quite well and as such he should know the veterans' portfolio equally well," Mr. MacLeod said. "I think that Peter is going to have a bit of hard time with the veterans' issue." He said veterans from across Canada have contacted him and offered their support – "That will make things difficult for Peter."

In an e-mail, Mr. MacKay said of Mr. MacLeod: "I commend him for his service to Canada. We welcome everyone to the democratic process."

Mr. MacLeod was a card-carrying member of the Conservative Party but became disillusioned – in part, after Alberta Tory MP Rob Anders slept through a presentation he made with another Afghanistan veteran to a Commons committee in 2012. The incident provoked controversy after Mr. Anders characterized the two veterans as "NDP hacks" for criticizing him for dozing off. The MP later apologized.

Although he hasn't been "green-lit" yet – the interview and background checks a person must go through before being allowed to run for a nomination – he is considered a preferred candidate by the Justin Trudeau team. In fact, he was approached by the Trudeau Liberals to run. Another local person is expected to contest the nomination, scheduled for later this month.

"It's certainly an interesting contrast," a key Nova Scotia Trudeau organizer said, asking not to be identified. "A former defence minister [and] a veterans' advocate.… It does play with that whole narrative about Harper and his government and the mistreatment and the disrespect for veterans. So in that sense it's a great little story."

The Trudeau Liberals are leading in the polls in Atlantic Canada – and there is bullish talk among some of them that they could sweep Nova Scotia in the federal election.

Last month, Mr. Trudeau attended two fundraisers in the province, raising close to $200,000 in two days, exceeding expectations. There are 11 federal seats in Nova Scotia; the Liberals and Conservatives each have four, and the NDP holds three. However, two Conservative incumbents have announced they are not seeking re-election.

Story continues below advertisement

One of the Harper team's Nova Scotia strategists scoffed at the Liberals' view they could defeat Mr. MacKay, noting that, in last year's provincial election, the three seats in Mr. MacKay's federal riding went Progressive Conservative despite a Liberal sweep. "Peter is extremely popular there and I think that part of the reason why we did so well provincially is because of Peter," the strategist said.

In addition, the Liberal organization in Central Nova suffered a setback in 2008 when then-Liberal leader Stéphane Dion made a pact with Green Party Leader Elizabeth May, who was running in the riding. To help her get elected, he did not run a Liberal candidate against her. She was unsuccessful in her bid to defeat Mr. MacKay – and some Liberals from the riding became disillusioned and left the party.

Mr. MacLeod, however, is not worried. He points to the fact that the provincial Liberals were able to win the Antigonish riding, which is part of Central Nova, in last year's election. He hopes to tap into that organization if he wins the nomination. Mr. MacLeod grew up in and around the federal riding – and has lived in Antigonish since 2009. His wife is a professor at St. Francis Xavier University there.

He served with the Princess Patricia's Canadian Light Infantry for 17 years and, for the remaining 10 years, he was in military intelligence. He sustained a number of injuries in training, including being shot in the leg, which led to his medical discharge four years ago.