Bernie Sanders has based his presidential campaign on a call for political “revolution,” which has energized his supporters eager for change in what Sanders calls the “establishment politics” that has created “a rigged economy” propped in place by a “corrupt” political system.

It is some of the most fiery rhetoric coming from the left heard from a major presidential candidate in decades, and his message has lifted Sanders from a little-known, independent Senator from a small state to a serious contender for the Democratic nomination — all in a matter of a few months.

But while Sanders’ message, and description of his own political ideology as “democratic socialism,” have built him a passionate and nationwide following, his history of left-wing activism and sometimes extreme-sounding statements dating back decades could provide dangerous ammunition for Republicans to aim at Sanders in a general election, some political experts now say.

Bernie Sanders as Mayor of Burlington, Vermont, in 1988, endorsed Jesse Jackson for president (Photo By Toby Talbot/Associated Press)

Going back to the 1970s and 1980s, Sanders has called for doing away with the Central Intelligence Agency, had an affiliation with the far-left Socialist Workers Party, which advocated eliminating the U.S. defense budget, and was chairman of the Liberty Union Party, which advocated a return to “local citizen militias” rather than a standing army.

A Gallup poll last year found that Americans would prefer to vote for an atheist, Muslim, or gay candidate than one who calls himself a “socialist,” with only 47 percent saying that a socialist candidate was worthy of a vote.

But Sanders has since softened most of the more extreme positions of his younger years, and he attempts to place his past statements in context whenever he is asked.

In fact, at a CNN Town Hall in South Carolina last week, anchor Chris Cuomo confronted Sanders directly on his position regarding the abolition of the CIA.

Bernie Sanders offered a lengthy response, as seen in the following video.

“It’s all too easy to imagine how gleefully Republicans would exploit Sanders’ youthful opposition to the CIA and his anti-military leanings if he were to be the nominee,” wrote columnist Michelle Goldberg in the online magazine Slate. “In a time of widespread panic about terrorism, the attack ads write themselves.”

Republicans have a history of seeking out seemingly outlandish facts or statements from the past histories of their Democratic presidential rivals, then ruthlessly exploiting them regardless of their true context, or even factual accuracy.

In the 2008 campaign pitting Republican John McCain against then-Senator Barack Obama, Republicans claimed that Obama “launched his political career” in the “living room” of William Ayers, a Chicago educator who, almost four decades earlier, had been a member of The Weather Underground, an outlaw, left-wing group responsible for several bombings in the late 1960s and early 1970s.

Bernie Sanders shortly after his election as mayor of Burlington, Vermont, in 1981 (Photo By Donna Light/Associated Press)

But though Obama and Ayers did know each other years later — Obama would have not yet become a teenager when Ayers was active in the Weather Underground — the Republican claims were found by fact checking groups to be false.

That attack ultimately failed, as Obama defeated McCain handily in the November election. But in 1988, the Republican campaign of then-Vice President George H.W. Bush was more successful.

Bush and his campaign repeatedly attacked the Democratic nominee, Michael Dukakis, for vetoing a bill that required teachers to lead students in the Pledge of Allegiance each school day, when Dukakis was governor of Massachusetts in 1977. Bush used the veto to portray Dukakis as dangerously unpatriotic.

Dukakis argued that the bill was unconstitutional and that Bush was “unfit to be president” if he believed it should have been signed. But the “pledge of allegiance” attack is considered a major factor in flipping what had been a 17-point polling lead for Dukakis in July into an electoral defeat in November.

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In 1984, Democratic candidate Walter Mondale pledged to “raise your taxes,” claiming that his Republican opponent, President Ronald Reagan, would also raise taxes, but lie about his intentions.

The part about Reagan supposedly lying was lost in the campaign, where Mondale’s “raise your taxes” quote survived to lead Mondale to one of the largest landslide defeats in U.S. history.

Bernie Sanders, perhaps unfortunately should he become the Democratic nominee, offered a similar pledge at a CNN Town Hall in January, promising, “We will raise taxes, yes we will!” as seen in the video below.

Sanders made his “raise taxes” pledge in the context of explaining his proposed “Medicare for All” program which he says will, on balance, result in a net savings for American households whose increased tax bill will, Sanders argues, be more than offset by their savings in insurance premiums.

But in the high-volume, high-velocity atmosphere of a presidential general election, the context is all but certain to be drowned out.

While polls show that Bernie Sanders must stage a dramatic political comeback to defeat Hillary Clinton for the Democratic nomination, if he pulls it off his advisers will need to be well-prepared for an onslaught of attacks based, even if unfairly, on Sanders’ long history of left-wing activism.

[Featured Photo By Alex Wong/Getty Images]