He asked the company in a tweet, "What kind of message are you trying to send?"
But the company also sells anti-Hillary Clinton apparel, including shirts that say "Hillary for Prison".
The online site is selling t-shirts with "IMPEACH 45" emblazoned across the front in big capital letters - a call to bring down the 45th US president, Donald Trump. Old Glory has sold more pro-Trump shirts than anti-Trump ones since the president has taken office, he said.
Other items echoing the anti-Trump sentiment were also available on the retail giant's website, including other T-shirts, coffee mugs and bumper stickers, made by several companies.
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Teespring had their shirts pulled off the Walmart website days later.
Walmart has caused outrage over its apparel before.
The outcry sparked a #BoycottWalmart trend on Twitter as users expressed their distaste for the chain promoting the impeachment of President Trump, echoing some Congressional Democrats. It was sold on its marketplace, which features products by many brands, and includes political t-shirts representing many different points of view.
In all of those cases, Walmart removed the products after consumer complaints, rather than screening them beforehand.
A Walmart spokeswoman did not return a request for comment.
Walmart has been targeted before by angry shoppers after controversial items have appeared on the platform. Last year, Walmart came under fire for selling a shirt that read "Rope".