US President Donald Trump's re-election merchandise, including flags being produced in China factories, would be subject to his proposed new tariffs against Chinese goods.

The flags bearing campaign slogans "Trump 2020" and "Keep America Great" are being produced at six or seven factories in China, with hundreds of thousands of flags ordered in total, according to some manufacturers.

The Keqiao Jiahao Arts & Crafts Company in Shaoxing, Zhejiang province, received the largest order — 90,000 flags measuring 3 feet by 5 feet.

From late May to July, the company manufactured 20,000 to 30,000 banners at its factory in Fuyang, Anhui province. They expect to complete the order by the end of the year.

By that time when those flags are ready to be shipped to the US, the party who placed the orders may have to pay more money, thanks to the Trump administration's tariffs on Chinese goods worth $200 billion.

Flags are among the goods targeted by the tariffs which are expected to start after the public comment period ending on Aug 30.

"I think what Trump is doing is lifting a rock only to drop it on his own toes," Yao Dan, owner of Keqiao Jiahao, told China Daily on the phone. "We Chinese supported him. But it (the tariffs) is a slap in the face."

Trump was campaigned on the promise of keeping more jobs in the US, but reports said his supporters walked around wearing "Make America Great Again" hats that were made in China.

Trump's re-election campaign on Saturday denied that it is using Chinese manufacturers to produce 2020 campaign flags in response to recent reports. Yao declined to name his client, but said they are based in the US.

In 2016, Yao was reported to have successfully predicted the US presidential election result through the orders of campaign flags.

"We produced more than 200,000 flags for Trump from May 2016 to the end of that year, but only 20,000 for Hillary Clinton," he said, adding, "We produced zero for Obama."

Yao said the flag industry would be impacted by the trade war somehow, since they have seen increased orders from the US. "We are currently working on over 200 patterns from US clients, mostly sports flags, police flags and rainbow flags," he said.

The impact will be limited because China enjoys advantages of cheap labor and materials, manufacturing capacity and environmental requirements, compared to international competitors like India and Vietnam, said Yao.

Even Trump's suppliers can't resist the temptation of cheap prices — the 3-by-5-foot flag sells for 5.5 yuan (81 cents).

Guangzhou Leben Outdoor Products Company is another contractor hired to manufacture Trump re-election campaign flags. They have produced 30,000 flags so far, and a total order of 80,000 flags is expected to be finished by October.

"Over 70 percent of our clients are from the US. We have sales persons communicating with them in English," said company owner Lai Xiong, who also declined to disclose the identity of the client who ordered the Trump flags.

Despite the possible impact from the tariffs, Lai doesn't seem worried about losing business. "China is the world's No. 1 textile supplier. Flags are fast moving consumer goods. Just like food, the demand is always there," he said.

Lai said it's unlikely he'll offer a discount to his clients if the tariffs are imposed. "They can complain to Trump. He started it after all," he said.