Sen. John McCain (R-AZ) garnered nearly 60 million votes in his 2008 presidential run against Barack Obama. In 2010, he won election to a fifth term in the Senate, receiving 58.7 percent of the Arizona vote. Now he’s the least popular senator in the country, at least with his own constituents, according to new Arizona poll results from left-leaning Public Policy Polling.

Just 30 percent of Arizonans approve of the job McCain is doing, while 54 percent disapprove, the poll found. McCain gets low approval marks from independents (25 percent) and Democrats (29 percent), but he fares only slightly better among the state’s Republicans (35 percent). Arizona’s state Republican Party formally censured McCain earlier this year for a “disastrous and harmful” record, including support for issues like immigration reform that are “associated with liberal Democrats.”

Related: McCain Censure the Latest Sign of GOP Fratricide

Jeff Flake, the Republican junior senator from Arizona, has a slightly lower 27 percent approval rating, the poll found, but his disapproval rating, at 47 percent, is also lower than McCain’s.

“The low opinion both Republicans and Democrats have of John McCain now means he could be vulnerable in both the primary and the general election next time around,” Dean Debnam, president of Public Policy Polling, said in the statement accompanying the poll results. “George McGovern lost his Senate seat eight years after losing his presidential bid and McCain could suffer a similar fate.”

The 77-year-old senator said earlier this year that he’s “looking very seriously” at running for a sixth term in 2016. The new poll, which surveyed 870 Arizona voters from Feb. 28 to March 2, found that McCain trails in hypothetical matchups with former Congresswoman Gabby Giffords and Richard Carmona, the Democratic former U.S. surgeon general who lost a 2012 bid to replace the retiring Arizona Sen. Jon Kyl. He would lead in a race against former Governor Janet Napolitano.

McCain has been a sharp critic of President Obama’s foreign policy, in particular, and he has also clashed with younger conservatives in the Senate, such as Tea Party favorite Ted Cruz (R-TX).

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