Bernie Sanders’ 2016 political brand is that of an independent in every sense of the word: a truth-telling crusader not beholden to party bosses, focused only on the issues and scrupulously avoiding the negative gamesmanship that has eroded voters’ trust in democracy. But political rivals of the Vermont senator, whose political career spans three decades, say he hasn’t been shy about engaging in those very practices – both in his bid for the Democratic nomination for president this year, and in previous elections for statewide offices. The campaign of Hillary Clinton, whom Sanders is chasing for the nomination, has repeatedly accused him of airing misleading television ads and sending direct-mail flyers that imply he has received the endorsements of news organizations and advocacy groups that either haven’t endorsed anyone or have backed Clinton instead.

Last month, representatives of the powerful Culinary Union in Nevada, a key constituency which has formally remained neutral and that is expected to play an outsize role in the state’s caucuses this weekend, slammed the Sanders campaign after staffers were caught wearing union buttons to gain access to employee dining rooms in Las Vegas.

Sanders also took heat in December when a staffer took advantage of a Democratic National Committee computer glitch and accessed the Clinton campaign’s proprietary digital voter information.

The Sanders campaign, which did not respond to U.S. News’ requests for comment Tuesday, has in the past denied any ill intent.

The campaign said its attempts to access Clinton campaign data during the DNC database breach – efforts to capture the data on 24 lists were confirmed by audits – were an effort to collect proof of a faulty system, not to take advantage of the problem.

Ultimately, the DNC’s initial action – to lock the Sanders campaign out of its own computerized voter data – inflamed supporters of the Vermont senator who already saw the Democratic Party as trying to rig the race in Clinton’s favor, and Sanders raised more than $1 million decrying the action.

But Sanders has several times been – and benefited from being – the Democratic establishment’s candidate of choice.

A self-proclaimed democratic socialist who caucuses with Democrats on Capitol Hill, Sanders decided to run for the Democratic presidential nomination even though he long insisted upon remaining independent. He has only recently begun to call himself a Democrat and embraced the party, a similar tactic he used in his run for Senate in 2006.

Back then, Sanders ran in the Democratic primary, defeating three other candidates, but declined the nomination. He then ran – and won – as an independent in the general election, while no Democrat appeared on the ballot.

At the time, Vermont Democratic Party officials described the agreement that allowed Sanders to make the switch as a “concession to political reality.”

“Bernie Sanders has by far the best chance of winning, and would work closely with and would respect Democratic leadership in Washington," then-VDP chairman Ian Carleton told the Boston Globe in July 2006. “Anyone who takes a practical look at Vermont politics will say that this is the best thing to do for the greater good here."

Sanders’ opponents, however, accused him of the very thing he and his supporters have claimed the DNC is doing for Clinton this year: giving an unfair advantage to the candidate the party establishment wants to win.

Peter Moss, one of the losing Democratic candidates, accused the VDP of conspiring to “anoint” Sanders.

“‘This is against the legislative intent to have the voters pick the candidates in primaries, not the political machines,” Moss told the Burlington Free Press in September 2006. Moss and others implied the party and Sanders struck a “backroom deal,” an accusation Sanders spokesman Jeff Weaver said at the time was “much ado about nothing.”

“The national Republicans wanted to split the progressive Democrat vote in Vermont, and we chose not to allow them to do that,” Sanders said in November 2006.

In 1990, editorials in the Vermont Times made similar accusations, never confirmed, of backroom shenanigans in which Sanders struck a deal to run for Vermont’s U.S. House seat with just token Democratic opposition, in exchange for opting out of a run for governor.

This year, the Sanders campaign has brushed off accusations of deceptive advertising – implied endorsements from the Des Moines [Iowa] Register, The [New Hampshire] Valley News, the AARP, the League of Conservation voters and veterans belonging to the American Legion – as mistakes.

But in his 1986 campaign challenging Gov. Madeleine Kunin, Sanders was accused of making similar insinuations, distributing a flyer that implied the endorsement of the Rutland Herald, and of sending a letter that suggested it had the support of the Vermont National Organization for Women.

Sanders’ 2006 Senate campaign was also accused of running so-called “push polls,” a tactic considered deceptive in which a partisan caller, masquerading as an independent pollster, asks a potential voter leading questions with the intention of spreading negative information about an opponent.

In March 2006, the Brattleboro Reformer reported that Sanders asked residents about his then-opponent, Republican candidate Richard Tarrant. In the article, Tarrant spokesperson Tim Lennon "accused Sanders of launching a negative telephone poll, but the Sanders campaign denied that, saying the poll is meant to collect information," according to the Brattleboro Reformer. "The new Sanders poll in Vermont has asked residents about Tarrant’s $8.8 million home in Florida, their impressions of recent layoffs at IDX and the company’s sale to ‘outside’ interests, Lennon said." Sanders' campaign said the 2006 poll was "a matter of gaining information."

"Congressman Sanders repeatedly reminds Vermonters that he has never run a negative advertisement," Lennon told the Reformer at the time. "The question is: why is Congressman Sanders testing personal attacks. The cost of candidates home has nothing to do with politics."



