At least Tom Mulcair doesn't have Donald Trump on his case.

But the NDP leader's dual citizenship could cost his party votes even though most Canadians aren't aware of it, a poll by Forum Research suggests.

More than one-quarter of voters said they would be less likely to vote for the NDP because Mulcair is a citizen of Canada and France.

"It's not going to be helpful in any way. It may have a bit of a drag on his prospects," said Forum Research president Lorne Bozinoff.

The Toronto-based polling firm asked 1,499 Canadian voters about Mulcair's citizenship.

Only 27% of Canadians are aware he has dual citizenship. He was born in Ottawa, but his wife Catherine is French and their children are citizens of both Canada and France. As the spouse of a French citizen, Mulcair was able to become "un citoyen." A similar number -- 26% of respondents -- said his dual citizenship would make them less likely to vote NDP.

Mulcair's dual citizenship isn't a secret, but hasn't been a prominent issue.

There were news stories in 2012, when Mulcair was running for the NDP's leadership, about Prime Minister Stephen Harper calling on him to renounce his French citizenship.

Harper has said he's a Canadian and only a Canadian.

Many Canadians recall when Liberal Leader Justin Trudeau was born in Canada on Christmas Day, 1971, the first son of then-prime minister Pierre Trudeau and his then-wife Margaret.

Mulcair has rebuffed calls to renounce his French citizenship, saying Canadians are diverse and understand people have connections to other countries through family ties or immigration.

"This issue has come up from time to time, so we thought we'd ask about it," Bozinoff said, explaining Forum Research didn't conduct the poll on behalf of a political party.

In the United States, citizenship is an issue for anyone hoping to occupy the White House. The American constitution requires a president to be a natural-born citizen.

Some Republicans have challenged Barack Obama's legitimacy as president, alleging he was born in Kenya and not eligible to hold the presidency.

During the 2012 presidential election Donald Trump famously offered to donate $5 million to charity if Barack Obama would merely show him his birth certificate.

corey.larocque@sunmedia.ca

Twitter: @Corey_Larocque

Citizenship facts:

- Canadian citizenship didn't exist before 1946. Liberal prime minister William Lyon Mackenzie King became Canada's first citizen in 1947.

- Liberal prime John Turner (1984) had dual citizenship. He was born in the United Kingdom.

- Canada's first two prime ministers, Sir John A. Macdonald and Alexander Mackenzie were born in Scotland. Macdonald used to proclaim: "a British subject I was born, a British subject I will die."

- To see Forum Research's poll on Mulcair's citizenship, visit http://poll.forumresearch.com/