Liberal Leader Stephane Dion brought in some high-profile party members to the Montreal riding of Outremont on Saturday, hoping to shore up support ahead of Monday's byelection.
"On Monday we'll have optimistic results. I'm quite confident," he told 麻豆影视.
A recent poll suggested Liberal candidate Jocelyn Coulon is trailing NDP hopeful Thomas Mulcair, a former Quebec environment minister.
An NDP victory would be seen as a serious blow to Dion's leadership, CTV's Craig Oliver reported Saturday.
"It's one of the safest Liberal seats in history," he told Newsnet.
The Liberals have only lost the riding once since 1935. A Progressive Conservative candidate won the seat in 1988, but only served one term.
"It is an important crossroads, because it's the first electoral test of (Dion's) party since he became leader," said Antonia Maioni, director of the McGill Institute for the Study of Canada.
Dion visited Outremont Saturday morning, and brought along Hockey Hall of Fame goaltender Ken Dryden and Justin Trudeau.
He said the Liberals will have to fight hard to keep the riding, but also said a surge in support for the NDP was partly due to frustration with the Conservative government.
"It's clear that the people in Outremont are looking for a way to express their protest against the current government," he said.
"Right wing is not something they want."
Mulcair attributed the jump to NDP Leader Jack Layton's guidance.
"The strong leadership of Jack Layton is one of our strongest suits, and the weakness of Stephane Dion is obviously a problem for the Liberal candidate," he said.
On Friday, a Unimarket-La Presse poll suggested Mulcair had a six percentage-point lead over Coulon.
If Mulcair wins, he would be the first NDP MP from Quebec since consumer advocate Phil Edmonston won a byelection in 1990.
The same poll hinted that the Conservatives could win a byelection in the Roberval-Lac-Saint-Jean riding Monday, where voters have traditionally backed the Bloc Quebecois.
The riding is also located in an area where the provincial Action democratique du Quebec made big gains in an election last March. The ADQ is philosophically similar in many ways to the federal Conservatives.
The third riding up for grabs Monday is Saint-Hyacinthe-Bagot, where poll numbers suggested the Bloc candidate has the most support.
With reports from CTV's Genevieve Beauchemin and The Canadian Press
