Politics watchers in the United States have long spoken about the “October surprise” that has the potential to upend the presidential race in the final stretch.

With 45,000 dock workers going on strike at dozens of ports across the US, such a moment may have arrived.

The decision by the International Longshoremen’s Association (ILA) union to walk off the job on Tuesday threatens to unleash economic chaos just weeks out from the November 5 vote.

Operations have come to a halt at 36 ports on the East and Gulf coasts, stretching from Texas to Maine, which together handle more than half of imports by sea.

While shoppers are not likely to notice any immediate changes at the checkout, a prolonged strike would play havoc with supply chains, resulting in shortages and higher prices for consumers.

Goods most at risk range from seafood and bananas, to clothing, electronics, cars and pharmaceuticals.

JPMorgan estimated ahead of the strike that a shutdown of the East and Gulf coast ports could cost the economy $5bn a day.

ILA President Harold Daggett has warned that the striking workers could “cripple” the economy if the union’s demands for a 77 percent pay rise over six years and a halt to port automation projects are not met.

“Cars won’t come in, food won’t come in, clothing won’t come in,” Daggett said in remarks broadcast on Fox News. “You know how many people depend on our jobs? Half the world.”

President Joe Biden, who has cast himself as the most pro-union leader in US history, has expressed support for the workers’ demands and rebuffed calls to use powers contained in the 1947 Taft-Hartley Act to order them back to work.

All of this spells potential danger for Vice President Kamala Harris, the Democratic Party nominee, at the very moment she is gaining voters’ trust on economic issues.

Recent polls have shown Harris, who is narrowly ahead in most surveys of the race, closing the gap with former President Donald Trump on who is best suited to handle the economy, which has long been viewed as one of the Democrat’s biggest vulnerabilities.

One likely reason for this is that US consumers, who laid much of the blame for higher prices on Biden, are starting to feel less of a squeeze on their wallets.

After peaking at 9.1 percent in mid-2022, inflation fell to just 2.2 percent in August, its lowest in more than three and a half years.

The US Federal Reserve last month announced its first interest rate cut in four years, a powerful signal that concerns about runaway prices are finally in the rearview mirror.

A spike in prices just as voters are heading to the polls would strike at perceptions that the economy has turned the corner on the Democrats’ watch.

Much of the risk for Harris would hinge on whether voters viewed her more as part of the incumbent administration or the candidate for change she has sought to portray to the public.

Harris is an unusual nominee given her late entry into the race following Biden’s withdrawal in July, but there is some evidence that voters see her as representing a continuation of the current administration.

In a New York Times/Siena poll published earlier this month, 55 percent of respondents said that Harris represented “more of the same,” compared with 34 percent who said the same about Trump.

Inevitably, Trump wasted no time trying to tie the strike to Harris, blaming the work stoppage on the “massive inflation created by the Harris-Biden regime”.

“Everybody understands the dockworkers because they were decimated by this inflation, just like everybody else in our country and beyond,” Trump told Fox News Digital shortly after the strike began.

Any effort by Harris to differentiate herself from Biden on the strike would carry its own risks, not least alienating union members who have traditionally voted Democrat.

Those are voters that Harris may be especially hesitant to take for granted after the International Brotherhood of Teamsters, one of the country’s biggest unions, last month broke with its tradition of supporting Democrats by declining to endorse a candidate for the first time in nearly three decades.

While it is impossible to know how the strike will affect the outcome of the election, the Harris campaign will not be happy about having to handle such a surprise with just five weeks to go.