"We're giving them until Friday midnight to respond," said Heather White, an organizer for the National Truckers Association, which represents about 1,700 truck drivers in southern Ontario.
She said the truckers want higher mileage rates, lower fuel prices or fuel-tax rebates, or a combination of those things.
Bill Wellman, association president, asked members to boycott Petro-Canada until midnight Friday, and go on strike if the governments fail to act by then.
Wellman said trucks would be asked not to block highways if a strike occurs, but he could not guarantee what action individual truckers might take.
Late last week, Ontario Transportation Minister Al Palladini promised to meet with federal officials if the truckers gave him a 48-hour grace period.