An executive representing ports where tens of thousands of workers went on strike this week made a series of critical and crude remarks about Joe Biden, tied Kamala Harris to concerns about over-taxation, and appeared to endorse a rightwing conspiracy theory.

David Adam, chairman and chief executive of the United States Maritime Alliance (USMX), attacked prominent Democrats in a string of social media posts uncovered by the Guardian.

It comes after about 45,000 dockworkers at ports along the US east and Gulf coasts walked off the job – the first such strike since 1977 – as part of a dispute between the USMX and the International Longshoremen’s Association over pay and automation.

The sweeping strike, disrupting 36 ports from Maine to Texas, has already raised fears of supply shortages and price increases on the eve of November’s election.

A month ago, when a LinkedIn user suggested that “everything Biden has touched in the past is turning to shit!”, Adam replied: “The runny kind….”

It was part of a discussion about how Biden’s student-debt relief plan was being held up in the courts. In another comment on the thread, Adam wrote: “If ya can’t get an American Democrat to pay what they borrrowed [sic], how you gonna get a California illegal immigrant to pay back their $150K loan the CA Dems are offering?”

Three months ago, another user appeared to endorse a popular conspiracy theory surrounding the emergence of a totalitarian world government while commenting on a video of Biden discussing immigration. “Did I miss the vote America took in agreement of One World Order? Treasonous actions have consequences!” they wrote.

“I think Kerry and Gates voted two thumbs up on that a few years ago …” Adam replied.

John Kerry was the Democratic presidential candidate in 2004, and served as secretary of state under Barack Obama and Biden’s climate envoy. Bill Gates co-founded Microsoft. Both men have been tied to debunked conspiracy theories surrounding secret global regimes.

USMX did not respond to multiple requests for comment on Adam’s posts.

Just a few weeks ago, Adam commented on a meme that claimed the US has a 48% fuel tax, which was debunked in 2022 by Politifact, when the same post was shared in Canada with the same claim.

He seemed to suggest responsibility lay with the Biden administration and Harris, however, writing: “Someone ask Kamala to explain why this is such and is she gonna fix it?!”

Earlier this year, when another user suggested Biden had smiled while walking away from a question, Adam commented: “Actually I thought he looked like he just sharted himself.”

When the strike began on Tuesday, Biden urged the port operators – represented by USMX – to give workers a “meaningful increase” in pay. Trump, meanwhile, blamed the strike on high inflation under Biden and Harris.

The timing of the strike, just weeks before the election, also raised questions about the ILA’s relationship with Trump. A photograph of the union’s president, Harold Daggett, meeting Trump in November resurfaced on social media this week.

After an assassination attempt on Trump in July, the ILA released a statement describing the 2023 meeting as “wonderful” and “productive”, and hailing Daggett’s “long relationship” with the former president.

The union has not made an endorsement ahead of next month’s presidential election. It backed Biden in 2020, declaring him to be “a true friend of the ILA and working men and women across America”.