Flake's statement, posted on his Facebook page, is in response to a Public Policy Polling survey that showed his approval rating among Arizona voters at 32 percent.

"Nothing like waking up to a poll saying you're the nation's least popular senator," Flake wrote. "Given the public's dim view of Congress in general, that probably puts me somewhere just below pond scum."

Fifty-two percent said they are less likely to vote for Flake in another election because of his vote on the background check bill.

Flake said his vote against gun background check legislation proposed by Sens. Joe ManchinJoseph (Joe) ManchinHeitkamp becomes first Dem to back Pompeo for secretary of State Trump eyes Cold War statute to keep coal burning: report Trump checkmates Democrats in sending Pompeo to North Korea MORE (D-W.Va.) and Pat Toomey (R-Pa.) is what's weighing down his approval numbers. The Senate voted 54 to 46 in favor of the legislation, six votes short of the 60 it needed to pass the chamber. 

"Now, notwithstanding the polling firm's leftist bent, I would assume that my poll numbers have indeed taken a southerly turn since my vote against the Manchin-Toomey background check proposal," Flake continued. "It was a popular amendment, and I voted against it."

The junior senator from Arizona also linked to an article by The Arizona Republic's Joanna Allhands which "captures the complexity of the issue" of that gun vote.