WASHINGTON – President Donald Trump on Wednesday singled out a four-page supplement that a Chinese-government run media company placed in Iowa’s largest newspaper as a sign that Beijing is losing the trade war with the U.S. — and meddling in the midterm elections.

“China is actually placing propaganda ads in the Des Moines Register and other papers, made to look like news,” Trump wrote on Twitter. “That’s because we are beating them on Trade, opening markets, and the farmers will make a fortune when this is over!”

Trump was referring to a four-page supplement that appeared in the Sunday edition of the Des Moines paper. The China Daily insert touted the mutual benefits of U.S.-China trade, built on concern about long-term market losses and highlighted President Xi Jinping's three-decades-long relationship with Iowa.

The government-backed English newspaper regularly buys inserts in U.S. newspapers, including the New York Times and the Washington Post.

Trump later told reporters at the United Nations' General Assembly meeting in New York that China is attacking the “farm belt” with ads and with statements. “I don’t like it when they attack our farmers," he said.

Earlier in the day, Trump accused China of interfering in the U.S. midterm elections as a way to undermine his aggressive trade policies.

“Regrettably, we found that China has been attempting to interfere in our upcoming 2018 election, coming up in November, against my administration,” Trump said at a meeting of the U.N. Security Council.

“They don’t want me or us to win because I am the first president to ever challenge China on trade,” he added.

Although China’s president, Xi Jinping, did not attend Wednesday’s U.N. meetings, his foreign affairs minister, Wang Yi, flatly rejected Trump’s accusations of election meddling.

“We did not and will not interfere in any country’s domestic affairs,” Wang said. “We refuse to accept … unwarranted accusations against China."

“It’s not surprising that China Daily sought to place advertising with the Des Moines Register, because the Register is Iowa’s largest news organization and Iowa farmers are disproportionately affected by China’s tariffs,” Register Executive Editor Carol Hunter said in a statement.

The Register is owned by Gannett, the same parent company that owns USA Today.

Experts speculated the insert was intended to undermine farm-country support for Trump's escalating trade war.

"I think it's trying to maximize pressure on the administration to change its trade policies toward China by attempting to show White House and Republicans that they're going to pay a price with the mid-terms," said David Skidmore, a political science professor at Drake University.

Trump has accused China of interfering in the U.S. midterm elections as a way to undermine his aggressive trade policies.

“Regrettably, we found that China has been attempting to interfere in our upcoming 2018 election, coming up in November, against my administration,” he said earlier Wednesday at a meeting of the United Nations Security Council in New York.

The U.S. and China have been engaged in a series of tit-for-tat tariffs as part of broader dispute over Chinese trade practices, including theft of intellectual property.

The Trump administration has levied duties on a total $250 billion worth of Chinese goods – roughly half of the Chinese-made products shipped into the U.S. China has retaliated by placing duties on $130 billion worth of U.S. goods.

Donnelle Eller of the Des Moines Register, USA Today reporters Deirdre Shesgreen and John Fritze contributed to this article.