The federal government says it's preparing legislation to prevent a strike at CN Rail.
Labour Minister Kellie Leitch says a strike at the rail carrier would hurt farmers and the forestry sector.
And she warns that any job action would undermine Canada's economic recovery.
"Our Conservative government is taking action to protect Canada's economy and Canadian grain farmers by indicating our intention to introduce legislation to make sure CN stays on track,'' Leitch told an impromptu news conference.
Leitch announced the notice of pending legislation after Canada's largest rail company received notice that one of its major unions could go on strike as early as Saturday.
The strike notice came days after the Teamster union's membership, which includes conductors and yard workers, rejected a tentative contract reached last fall and covering 3,000 employees at Canadian National Railway (TSX:CNR).
Saskatchewan Premier Brad Wall had called on Ottawa to step in before a strike even begins.
In a letter to Transport Minister Lisa Raitt, Wall said a strike would be unacceptable at a time when farmers are already having trouble moving a bumper crop of grain.
However, Leitch indicated that legislation would only be introduced should a strike be launched.
"We have a 72-hour strike notice that has been put in place. That comes into effect, they could go on strike as of Friday evening going into Saturday at one minute past midnight,'' the minister said.
"And our intention would be to bring them back to work.''