Just days after he took the helm of the Senate Armed Services Committee, John McCain, R-AZ, stood next to several hawkish Republican senators and attacked President Obama in typical McCain fashion.

He slammed the White House for releasing prisoners from the military’s Guantanamo Bay prison, even though McCain held that very position for a decade, from 2003 to 2013.

“The prison is a symbol of torture and justice delayed,” McCain said in November 2013, reading from a letter from 38 retired military officers on the Senate floor. “More than a decade after it opened, GuantÃ¡namo remains a recruiting poster for terrorists, which makes us all less safe.”

As late as mid-December, McCain had been saying he backed Obama’s effort to close the prison. But last week, McCain abruptly announced that he and other Senate hawks would be co-sponsoring a bill to bar the White House from releasing prisoners who have never been charged and the military had cleared for release.

“This administration never presented to the Congress of the United States a concrete or coherent plan,” McCain said, offering a thin rationale because he knew that congressional Republicans have been blocking Obama's efforts to close Gitmo for years.

This about-face was merely the latest example from McCain in a long career that has been marked by an astounding record of what pundits call flip-flops, the polite word for opportunism, hypocrisy and outright back-stabbing.

“What the heck has happened to John McCain,” CNN.com’s Sally Kohn wrote last July, in another high-profile example. “First he flip-flopped on immigration reform…Then he flip-flopped on legislation meant to address the dangers of climate change… And now we have Bowe Bergdahl.” McCain, who is granted too much deference because he endured years of captivity in the Vietnam War, was all for bringing the captured soldier home in a prisoner swap with the Taliban—until he wasn’t, which the Washington Post derided, earning him an “upside-down Pinocchio, constituting a flip-flop.”

Longtime McCain watchers are used to shaking their heads. Those covering his 2008 presidential campaign, which was mislabeled the “Straight Talk Express,” compiled lists of dozens and dozens of flip-flops that traced an ever-accelerating turn to the right.

“In theory, John McCain’s right-wing madness could come to an end on Tuesday, when he is expected to prevail over former Rep. J.D. Hayward in Arizona’s Senate primary,” MotherJones.com wrote in 2010, when he beat a Tea Party challenger. “In fact, his transformation from aisle-crossing, party bucking maverick to cookie-cutter conservative has been years in the making.”

MotherJones focused on four issues illustrating McCain’s high-level hypocrisy: he was for comprehensive immigration reform before he wasn’t; he was an advocate for stricter gun controls before he wasn’t; he wanted to end the military’s ban on gay soldiers but then didn’t; and he backed a cap-and-trade system for climate change emissions before he changed his mind.

“His choice of Sarah Palin as a running mate was the final blow for some of his truest believers, who saw it as political pandering at its worst,” MoJo's Suzy Khimm wrote, referring to to his supposed political independent streak. “But the failed White House run was just the beginning of McCain’s transformation into an ideologue.”

Today, with McCain chairing the Senate Armed Services Committee—which writes much of the Pentagon budget, and boosts his power and influence—McCain is poised to wreak real havoc. The day after the president’s State of the Union speech, he went after Obama’s claim that America has emerged from crisis. Of course, Obama was talking about the domestic economy, but McCain seemed to take it as an invitation to rechallenge the Democrat who stopped him from becoming president in 2008.

That year, Steven Benen, who is now with MSNBC, listed 61 flip-flops by McCain on almost every issue in an extensively documented AlterNet report. Of these, 18 concerned national security policy, foreign policy, and military policy—all areas that are touched by the Armed Services Committee.

On national security, McCain was against warrantless wiretapping until he was for it. He said Gitmo prisoners deserved some kind of trial, until he changed his mind. He opposed indefinite detention by the military until he didn’t. The Vietnam War prisoner of war who was tortured wanted to ban waterboarding—until he changed his mind. He slammed the White House’s use of military drones in Pakistan until he decided to support it.

On foreign policy, McCain was for kicking Russia out of the G8 economic club until Obama pushed for that after war broke out in Ukraine. He supported normalization of relations with Cuba but now opposes it. He believed the U.S. should engage with Hamas and with Syria’s dictator, but no longer. He backed the Law of the Sea convention but now opposes it. He was against divestment from South Africa but now says backed it.

On military policy, he claimed that he was the “greatest critic” of Secretary of Defense Donald Rumsfeld’s Iraqi policy, until he reversed course a year later. He has been on both sides of the fence with a long-term U.S. troop presence in Iraq. Before the Iraq invasion, he predicted the war woud be short and easy, but now it is hard and unending. He repeatedly lambasted Obama’s announcement of troop withdrawals, but then took credit that most troops would be home by the end of 2013. He opposed expanding veterans benefits in the GI Bill before he reversed course.

These examples have special salience because of McCain’s new Senate chairmenship. They are augmented by many others—remember him slamming Texas Sen. Ted Cruz’s “wacko bird” efforts to derail Obamacare, before he favored its repeal? Or his flip-flops on reproductive choice (pro-Roe v. Wade before favoring repeal), or on the environment (against offshore drilling before being pro-drilling), or on tax cuts for the rich (opposing them before they passed under George W. Bush and then rejecting repeal).

This is a dizzying array of political about-faces. They more than suggest that McCain’s judgment is as opportunistic as it is unreliable. It is astounding that a senator who is this fickle is now one of America's top civilian military commanders.

The Associated Press reported that McCain said his new Senate role was to educate the chamber—of “which 46 of 100 members are in their first term, some with little foreign policy experience.” He plans to bring in a parade of hawks to testify at his committee.

“He’s an anarchist,” Glenn Beck, the rightwing talk show host said a year ago, after he changed his Obamacare stance. “I’d like to call him the good senator from Arizona, [but] I think he’s a lousy senator from Arizona – when the lousy senator from Arizona decides, ‘Oh, wait a minute. Now the political winds have changed, now he wants to jump on [whatever bandwagon presents itself].”

Whether the correct word describing McCain is opportunist, hypocrite, or anarchist—and perhaps with Beck, it takes one to know one—it’s clear that a newly empowered McCain is as unpredictable as he is dangerous. And now he has a Senate chairmanship podium and the power of the Pentagon purse at his disposal.