Seldom have soybeans been so political. In the swing state of Iowa they are big business and right now that business is hurting.
The farmers who overwhelmingly backed Donald Trump in 2016 – catapulting him into the White House – are suddenly bearing the brunt of the president’s trade war with China.
Beijing’s retaliation to Mr Trump’s steel tariffs has targeted soybeans. China is the largest buyer of the crop, at $14bn (£11bn) last year.
As Iowa farmer Dave Walton told me: “We are in the crosshairs.”
He showed us around the rural property his family have farmed for over a century and explained how US soybean prices have dropped about 20% since March when the trade war began.
But the farmers know they have power in their hands.
With mid-term elections looming in November, they have the chance to at least send a message to the White House.
“There are some farmers here who are really upset,” says Mr Walton, who is a director of the Iowa Soybean Association.
“And there are others who are prepared to see how things go.”
It is a clear warning to the president in a state that is being targeted by the Democrats with the trade war in mind.
The clock is ticking as Republicans work to hold the support of the farmers by pledging $12bn in aid.
But that has backfired to some extent with many farmers insisting they want “trade not aid”.
Our journey across Iowa showed that, so far, most farmers and farm workers still support the president’s push for better trade deals.
He also retains broader support in a state where many people simply believe he is “on their side” or “talks our language”.
They are also looking beyond the tariffs at the wider economy and see things going well
But the red lights are flashing for Mr Trump. How long that support will last if the tariffs remain and prices continue to fall is anyone’s guess.
The Des Moines Register newspaper did not endorse candidate Trump in 2016, backing Hillary Clinton instead.
It lost then, but it is now warning President Trump that the patience of the Iowa soybean farmers is not unlimited: “Iowa farmers’ angst grows as tariffs mount,” runs the front page headline.
Local economists estimate the trade war could cost local farmers as much as $624m.
Mr Trump knows the voters who helped him win in 2016 could cause him real trouble in the mid-terms.
Addressing a rally a week ago, the president said: “Our farmers can take it. They are great guys, they can take it.”
And he’s right. They are taking it – for now.