Sen. John McCain, a man whom millions of Americans once chose to be their president, now faces a potentially uphill Senate reelection fight in 2016. According to Public Policy Polling, McCain is the least popular senator in the country — something of an accomplishment in itself.

PPP summarizes the bleak results for McCain: "John McCain is unpopular with Republicans, Democrats, and independents alike and has now become the least popular Senator in the country. Only 30% of Arizonans approve of the job McCain is doing to 54% who disapprove." And that doesn't matter much by party, either. Republicans, Democrats, and independents all view McCain about equally. So at a net approval of -24 percent, no senator is viewed less favorably by his state than McCain.

There are some caveats. PPP's full Senate data set doesn't include every senator, since not every senator has been polled. McCain may be more popular than, for example, North Dakota's senators! So you know. Glimmer of hope. But even Mitch McConnell's most recent numbers are higher than McCain's, and McConnell has been flirting with the depths of popularity for a while.

McCain is helping Arizona achieve a particular distinction: Arizonans view their senators less favorably than basically any other state. (Sen. Jeff Flake has had his own issues.) The only state with less popular senators is Montana. (On the map below, the average net favorability of the state's senators is shown. More red, higher opinion of the state's senators.)

The key to being popular in the Senate? Represent a state at the political fringe, from the political fringe. The states that like their senators the most are Wyoming and Vermont. Probably not terribly useful advice for John McCain.