T-shirts, coin purses and posters that show President Barack Obama portrayed as Chairman Mao are normally available for sale at the Great Wall. But on Sunday, when First Lady Michelle Obama visited the Chinese tourist spot with her daughters, the so-called "Obamao" souvenirs were no where to be found.

"We don't have them anymore," said one peddler, a woman who declined to give her name. "But if you come back next time, you might find them. You could come tomorrow," the woman said.

China Real Time managed to find, hiding in the back of many others, one army-green-colored shirt that displayed an Andy Warhol-like picture of Mr. Obama wearing Mao Zedong's cap. Under it were the words "Serve the People" written in traditional Chinese script. The vendor who owned it declined to sell it, saying they weren't for sale Sunday. She was willing to sell other T-shirts, such as "I climbed the Great Wall" for 180 yuan, about $29.

It's unclear who issued the verdict for the cleanup. Street vendors declined to comment. Such sweeps are common during high-profile visits in China. Vendors at well-known markets for pirated goods in Beijing are sometimes made to put away the name-brand knockoffs during high-level trade talks with the U.S. or European Union. Souvenir vendors also tucked away "Obamao" shirts in 2009, during Mr. Obama's visit to China.

Mrs. Obama is on a weeklong trip to China, during which she met with her Chinese counterpart Peng Liyuan and pitched the value of overseas studies to area schools and universities. On Sunday, Mrs. Obama and her daughters traveled to the Great Wall, climbing the Mutianyu section, which is farther from central Beijing than the well-traveled part of the wall President Obama went to in 2009.

The T-shirts, which portray Mr. Obama dressed in a Communist Party army green cap with a red star on it, have become common tourist trinkets at the Wall during Mr. Obama's time in office.

Prices of the Obamao shirt vary based on haggling capabilities of the buyer.

--Laurie Burkitt