The union that represents workers on the St. Lawrence Seaway, the waterway that links the Great Lakes and the Atlantic Ocean, has extended a strike deadline to Monday at 5 p.m. ET/2200 GMT.
A strike would close the key shipping route. Five locals of Unifor, Canada's largest private sector union, gave notice on Tuesday that they could strike midday on Friday.
Unifor said talks would continue through the weekend: "We remain hopeful that a deal can be reached," said Unifor National Representative Joel Fournier in a release.
(Reporting by Allison Martell; Editing by James Dalgleish)