Dockworkers have walked out of every major port on the US East and Gulf coasts, marking the beginning of a strike that could ripple through the world’s largest economy and cause political turmoil just weeks before the presidential election.

Longshoremen going on strike at East Coast ports in the US could cost the US economy $5 billion a day and cause holiday shipping delays, experts say.

Transportation and warehousing sectors are poised to first feel the pinch, with a broader economic fallout expected if the strike drags on.

The union representing U.S. dockworkers signaled that 45,000 members will walk off the job at midnight, kicking off a massive strike likely to shut down ports across the East and Gulf coasts

JPMorgan estimates the economic loss from the shutdown of every major container port from Houston to Miami and New York-New Jersey will be between $3.8 billion and $4.5 billion per day.

A dockworkers' strike is set to shut down ports across much of the US indefinitely, threatening significant trade and economic disruption ahead of the presidential election and the busy holiday shopping season.

Workers who load and unload shipping containers from cargo ships are at an impasse in labor contract negotiations.

The International Longshoremen’s Association says they’ll walk off the job at midnight if they can’t reach a deal on their contracts with the United States Maritime Alliance.