Senator Bernie Sanders (I-Vt.) made waves as a democratic socialist presidential candidate. Here's what you need to know about being a democratic socialist and how it's different from socialism. (Alice Li/The Washington Post)

UPDATE: Almost exactly a month after first proposing it, Sen. Sanders is giving a speech Thursday on what it means to him to be a socialist. Specifically, a democratic socialist, which is the Democratic presidential hopeful's particular strain of a political philosophy that many Americans, almost by definition, are wary of.

Sanders has a big hill to climb pitching his ideas to totally transform the nation: A June Gallup poll showed more than half of Americans say they wouldn't vote for a socialist, preferring instead to vote for a Muslim or atheist. Sanders is speaking at 2 p.m. Eastern time at Georgetown University in Washington, D.C., ostensibly to try to change that.

The speech is a big moment for Sanders in other ways. He has been reluctant to embrace the term "socialism" throughout his three-decade-long career in politics. Here's a history of his wary relationship with it:

Sen. Bernie Sanders (I-Vt.) didn't set out to be America's champion for socialism. He kind of backed into it.

To be clear, Sanders has always had socialist leanings. In the 1970's, he volunteered to run as a sort of sacrificial candidate for the U.S. Senate for the left-wing Liberty Union Party of Vermont. He served as an elector for the 1980 Socialist Worker Party nominee, Andrew Pulley.  

But Sanders stayed away from the s-word even after winning his first major election later that year as mayor of Vermont's largest city, Burlington.

"It never came up," said his friend and supporter in those years, Greg Guma. Guma,author of "The People’s Republic: Vermont and the Sanders Revolution," said Sanders talked about his political philosophy only when the media branded the new mayor as a socialist — Guma would say outed him — and he was forced to respond to questions about his political philosophy. 

Today, Sanders gives full-throated defenses of his version of socialism. As one of the Democratic Party's leading presidential candidates, he got front-runner Hillary Clinton to debate with him the merits of it in the party's first presidential debate Tuesday. He says he's preparing "a major speech" to define his particular branch, democratic socialism. It's probably safe to say America would not be talking about socialism versus capitalism in 2016 without Sanders.

But Sanders often only brings up the socialist label when asked about it. His role as the movement's standard-bearer in America is a role he has seemed reluctant to embrace and is tweaking even to this day.

Here is Sanders's evolution on using the term "socialism," in his own words:

Early on: Avoiding the s-word


Greg Guma, who worked with Bernie Sanders and later wrote a book about him, shows off old articles and photos. (Jabin Botsford/The Washington Post)

The '70s and '80s in America were very different times politically. Sanders and his allies avoided the term "socialism" at all costs for fear of being branded as communists, Guma said. When Sanders ran for the U.S. Senate in 1971 as a candidate for the Liberty Union Party, here's what he wrote of his strategy in his 1997 autobiography, “Outsider in the House":

"Wealth=power, lack of wealth=subservience. How could we change that? The ideas I was espousing were not ‘far out’ or ‘fringe.’ Frankly, they were ‘mainstream.’ ”

First win: A stump speech without the s-word


(Jabin Botsford/The Washington Post)

But as The Washington Post's David Fahrenthold details, running under the umbrella of a left-wing party was getting Sanders nowhere fast. So he switched to independent and stunned the city of Burlington in 1981 when he beat the five-term Democratic incumbent by 10 votes.

In that first election, socialism didn't come up at all, Guma said. Sanders campaigned mostly on local issues and avoided discussions of political philosophy.

But it was clear his philosophy was driving his politics. United Press International went to Burlington to catch his swearing-in. What Sanders said was to form the basis of his stump speech for the next 34 years:

''In America today, the rich are getting richer, the poor are getting poorer and the millions of families in the middle are gradually sliding out of the middle class and into poverty.

''In the final analysis, the people of America are going to have to say that the wealth, labor and natural resources must be used to benefit all the people, not just a few super-rich.

At the same time, he said he has no ''great sadistic desire'' to destroy the city's business community, and would try to work with businessmen on city projects.

Still, Sanders didn't run from the term when asked about it. In a 1983 reelection debate, according to the Associated Press, he said this:

"I am a socialist; of course I am a socialist," he said. "To hold a vision that society can be fundamentally different, to believe that all people can be equal — that is not a new idea."

Congress: Talking about but downplaying socialism


(John Duricka/The Associated Press)

Sanders's election to Congress in 1990 was a similar political surprise. Once he got to Washington, Sanders was arguably the loneliest person there: He was the sole representative from his state, the first socialist lawmaker since the 1920s and the first lawmaker to not be a member of either party in at least 40 years (he tried to caucus with the Democrats but was rebuffed).

Sanders focused on his status as an independent more than any other of his firsts:

"I am extremely proud to be an independent," he told the Associated Press in 1991.

And when he was asked to explain his socialist philosophy, he talked it down, telling the AP: "All that socialism means to me, to be very frank with you, is democracy with a small 'd.' Our goal is to create a society where you don't have such a gross inequality in terms of wealth and power, and to provide more political equality for working people and poor people."

Senate: No escaping the socialist label


(The Colbert Report)

Sanders's election to the U.S. Senate in 2006, with broad support from his home state, drew loud headlines in the national press, such as "Socialist leads in Vermont polls" and  "Cantankerous Sanders likely to be first socialist in U.S. Senate."

On the national stage, there was no escaping the socialist label. It was the first — and only — question that Stephen Colbert, then-host of Comedy Central's "The Colbert Report," asked Sanders in 2008 during an interview.

"So you're a socialist," said Colbert, playing his ultra-conservative alter ego. " That's like half of Chicago Fire saying, 'I'm an arsonist!' "

Sanders defended his socialism much the way he had his whole career: By focusing on the impact his socialist policies would have. Not for the first time, he brought up capitalistic European countries with socialist policies to make his point. Here are excerpts from his conversation with Colbert: 

SANDERS: The reality is there are many countries in Scandinavia and Europe who have done things like provide health care to every man, woman and child as a right to citizenship.

COLBERT: Need I remind you this is not Scandinavia or Europe.

SANDERS: Need I remind you we have 47 million Americans without any health insurance, and we spend twice as much as any other country.

COLBERT: That's class warfare. You're talking about redistribution of wealth.

SANDERS: I am.

Presidential race: Socialism's reluctant standard-bearer


(John Locher/AP)

Today, Sanders frames his "democratic socialist" policies as the best, last hope to save a torn America. There is much more urgency to his message that wealth needs to be redistributed:

"I think most Americans understand that our country today faces a series of unprecedented crises," he said by way of introduction at the first Democratic presidential debate. Later on, when CNN host Anderson Cooper asked Sanders to explain why he thinks there's room for a socialist in presidential politics, Sanders explained.

"And what democratic socialism is about is saying that it is immoral and wrong that the top one-tenth of 1 percent in this country own almost 90 percent — almost — own almost as much wealth as the bottom 90 percent," he said. "That it is wrong, today, in a rigged economy, that 57 percent of all new income is going to the top 1 percent."

Presidential race 2.0: Socialism's willing standard-bearer?


(Lucy Nicholson/Reuters)

But Sanders still rarely brings up his socialist label unless he is asked. That is, until Sunday, when he announced he was going to give a yet-to-be-scheduled speech on what it means to be a democratic socialist.

The next phase of Sanders's evolution with the term is to be continued.