An employee stacks items to be shipped at the Amazon.com fulfillment center in Phoenix, Arizona.

Two high-profile Senate Democrats are asking Amazon for answers about its "Amazon's Choice" badge, saying the recommendation engine could potentially be deceiving consumers into buying "inferior" products.

In a letter to Amazon CEO Jeff Bezos on Monday, Sen. Bob Menendez (D-NJ) and Sen. Richard Blumenthal (D-Conn.) asked for more clarity on how the Amazon's Choice program works, citing a recent BuzzFeed report that showed it often endorses defective or poor quality items.

"The badge may be misleading consumers into thinking the products that receive this distinction are the best available products, when in fact some of these products are of an inferior quality," the senators said.

The letter is the latest example of Washington's growing concern of Big Tech, specifically regarding the control Amazon has over consumer behavior as more shopping activity moves online and to mobile devices. In December, Blumenthal wrote a letter to Bezos arguing that Amazon's policy of blocking third-party sellers from offering lower prices on rival sites would "stifle market competition." Three months later, Amazon removed that policy.