Rob Wildeboer may have to decide as soon as Thursday whether the Canadian trucker protest that is blocking a key bridge between the United States and Canada will require him to furlough some of his several thousand factory workers.

Wildeboer, 62, the chairman of Martinrea International, which produces components for every global automaker, said Wednesday that the protests are within hours of halting some of his production lines. The company's engine blocks, transmissions, subframes and brake lines can be found in GM Sierra pickup trucks, Ford Escapes and Jeep Grand Cherokees.

Each day, Wildeboer's trucks make 38 trips across the Ambassador Bridge between Windsor, Ontario, and Detroit, shuttling half-finished products between company plants in both countries. The shipments are just part of $300 million in daily commerce that transits the aging steel span and is imperiled by the traffic-snarling protest of Canada's coronavirus restrictions and vaccine mandates.

For the auto industry, the borders between the United States, Canada and Mexico were effectively erased nearly 30 years ago by a North American trade deal. The industry has developed since then into a tightly choreographed industrial ballet that relies on parts arriving at a factory just in time to be used.

"We make a part Monday morning, it's probably on a vehicle by Wednesday," Wildeboer said.

The partial blockade of the Ambassador Bridge, now in its third day, threatens to derail the normal handoff from one factory to the next. A lengthy impasse, like the original "Freedom Convoy" that has jammed the streets of Ottawa for 11 days, would be likely to send layoffs rippling through factories in both countries.

Already, Ford and Stellantis have pulled back on production in their Ontario plants.

"The Windsor Assembly Plant had to cut short its first and second shifts on Tuesday due to parts shortages," Stellantis said in a statement on Wednesday. "The plant resumed production this morning. We continue to work closely with our carriers to get parts into the plant to mitigate further disruptions."

Ford did not respond to a request for comment.

Toyota said Wednesday that it was facing "shortages affecting production at our North American plants," including in Canada, but the Japanese automaker said it did not "anticipate any impact to employment at this time."

Magna International, an Aurora, Ontario-based supplier of vehicle components including chassis and seats, said it had shifted some of its shipments to alternative border crossings because of the bridge obstruction.

White House press secretary Jen Psaki said administration officials were working with their Canadian counterparts and industry executives to ease the damage to the auto industry, U.S. agricultural exports and the flow of workers between the United States and Canada.

"We're very focused on this. The president is very focused on this," Psaki said.

At the Ambassador Bridge, one lane across the Detroit River remained open on Wednesday, permitting limited traffic to trickle into the United States. Trucks bound for Canada are being rerouted to the Blue Water Bridge in Sarnia, Ontario, about 60 miles away. Given the crush of vehicles and resulting delays in Sarnia, the longer route is adding three hours to the trucks' customary journey, Wildeboer said.

Martinrea is a "Tier 1" industry parts maker, meaning it directly supplies giants such as GM, Daimler, Bentley and Honda. Headquartered in Vaughan, Ontario, the company has almost 16,000 employees, including about 5,000 production workers in the United States and 2,500 in Canada.

Martinrea plants can be found in Ohio, Michigan, Indiana, Kentucky, Mississippi, Tennessee, Alabama and Missouri.

If normal commercial flows are not restored quickly, some Martinrea operations will be forced to halt, Wildeboer said. Three of the company's facilities near London, Ontario, will be among the first to feel the blockade's effects.

"We make big stuff," Wildeboer said. "We can't keep production going and have stuff piled up in our yards. The yard would be full in a day and a half."

Nearly two years into a pandemic that has upended normal life, Wildeboer is sympathetic to protesters' frustration over the Canadian government's requirement that truckers be vaccinated. If it were up to him, he would scrap the mandate, since 90% of truckers have already been vaccinated, and the rest could easily be assigned to domestic routes.

But his sympathy ends where the economy-strangling blockade begins. The mushrooming protest started with hundreds of tractor-trailers jamming the streets of Ottawa and sounding their air horns, before spreading to Windsor.

The Ontario Trucking Association issued a statement disavowing the protests and insisting "most protesters have no connection to the trucking industry." Likewise, Canadian press reports from the Ambassador Bridge said big rigs there are outnumbered by pickup trucks and sedans, suggesting many protesters come from other segments of society.

Automakers already are struggling to supply dealers with enough vehicles to keep pace with surging consumer demand. The bridge protest only complicates those efforts. On Wednesday, the Canadian Vehicle Manufacturers' Association, which represents major producers including the local arms of Ford, GM and Stellantis, urged an end to the blockades by truckers and their supporters.

During the pandemic, the auto industry has endured a roller coaster of plant closures, the worst sales slump since the 2008 financial crisis, an unanticipated recovery and surprising shortfalls of computer chips needed in modern vehicles.

Martinrea has struggled more than most. The company's share price is down almost 31% over the past year, nearly three times the decline in a Standard & Poor's auto industry index.

The company lost $13.5 million in the third quarter last year after making a $34.4 million profit in the same period one year earlier. Briefing investors on the financial performance, Wildeboer offered a blunt verdict: "Q3 kind of sucked."

Although conditions improved in the last three months of the year, new supply headaches are constantly emerging. Last week, one of Wildeboer's customers managed to secure the computer chips it needed but was forced to shut down for three days anyway because it couldn't obtain enough vehicle headlights, Wildeboer said.

His U.S. plants are battling the same labor shortfall that afflicts other employers. European facilities are being hammered by high energy costs. Supplies of resin, used in injection-molded plastic parts, also remain scarce.

"We're kind of used to getting punched in the face," Wildeboer said, adding that he is "medium optimistic" about prospects for finding an early resolution to the impasse at the bridge.