Prize fights are a big deal in Las Vegas, so perhaps there is no better location for the first Democratic presidential debate than in the heart of Sin City.

The much-anticipated faceoff between main rivals Hillary Clinton and Bernie Sanders on Oct. 13 at the Wynn Las Vegas casino in Nevada could be a watershed event in the 2016 presidential campaign.

The stakes couldn’t be higher for Sanders, who is gaining in national polls, but remains a relative unknown to much of the general electorate. At the Las Vegas debate Sanders has a chance to introduce himself — and his policies — to an audience of millions.

However, Sanders, who has largely honed his debate skills in local contests, isn’t spending a lot of time on debate prep, according to his campaign — even though Clinton comes to the primary bout with more presidential debate experience.

Still, former rivals say the Vermont senator could be a formidable challenger in ring.

“He delivers his message so well that when he debates Hillary, he will kill her,” said Rich Tarrant, a Republican who ran an unsuccessful senatorial campaign against Sanders in 2006. “She doesn’t think on her feet at all, but he does.”

Tarrant was among 10 people VTDigger interviewed who have squared off against Sanders in debates that date as far back as Sanders’ unsuccessful run for governor in 1972 to his most recent Senate campaign in 2012.

While some of his former rivals believe Sanders has a fighting chance against Clinton, others think the junior senator from Vermont will have a hard time breaking free from the provincial echo chamber of Green Mountain politics.

But there is one thing the also-rans agree on: Sanders’ fluency and rhetorical consistency will be a major strength on stage.

Finding his inconsistencies

Judy Stephany, a Democrat who ran unsuccessfully against Sanders in 1983 when he was elected mayor of Burlington, says Sanders views himself as “the Messenger.”

“My sense of him has always been that he is a politician who puts belief in policy and desire to make policy change at the forefront of what he does,” Stephany says.

Because Sanders is supremely confident in his message, he doesn’t need to exhaustively prepare for the Las Vegas debate, according to Michael Briggs, communications director for the campaign.

Briggs says Sanders won’t practice against a Clinton surrogate, for example. The campaign, however, hasn’t ruled out the possibility of holding some sort of mock debate.

“Some candidates want you to rebuild the entire set so they can feel exactly like they are going to feel in real life,” Briggs said. “I don’t think Bernie needs that kind of over-the-top preparation for this.”

One of the remarkable features of Sanders’ four decades in politics is just how little his stances on issues have changed. While other politicians shift positions over time to accommodate constituencies, lobbyists and funders, Sanders tends to stubbornly stick to policy decisions — regardless of whether they are popular or not.

Reforming campaign finance laws, for example, has been a feature of his congressional campaigns for decades, and it is a cornerstone of his presidential platform. Sanders began railing about the corrosive effects of corporate money in politics after he lost the 1986 Vermont gubernatorial race, and the points he makes on the issue are virtually unchanged today. If anything, his rhetoric intensified after the 2010 U.S. Supreme Court decision in the Citizens United case, which allowed unlimited spending on behalf of candidates.

Sanders has called on the court to overturn the ruling, and has criticized other candidates, including Hillary Clinton, who rely on wealthy donors to fund their campaigns. Sanders himself has eschewed money from corporations, PACs and the super wealthy.

His signature issue — income inequality — is a drum he’s been beating since his early days as a Liberty Union candidate, and later as mayor of Burlington, where he talked about the disenfranchised, “the poor, the working class and the elderly.” Sanders put the needs of regular people first, political observers say, and over time he has simply changed the numbers he uses to illustrate his point that “the rich are getting richer and the poor are getting poorer.”

In a 1998 House debate, he talked about how the richest 1 percent in the United States had more wealth than 100 million Americans. He now says the richest one-tenth of 1 percent have as much wealth as the bottom 90 percent.

Sanders has also long been a proponent of raising the minimum wage. Back in 1993, in an aggressive House floor speech, he proposed a $5.50 an hour base hourly wage for all Americans. Now he wants a $15-an-hour minimum wage.

While his messaging on the economy has been consistent, Sanders has a mixed record on gun control and the arming of Israel.

As Politico and others have reported, Sanders was helped by attack ads aired against incumbent Peter Smith in the 1990 House election, which Sanders won.

Smith said he remains proud he took a stand against the sale of assault weapons during the 1990 election, but that he could have maneuvered better politically in his race against Sanders.

“Whatever other issues were in the race, there’s no doubt the NRA’s support of Bernie was a turning point in the campaign,” Smith said. “The attack ads against me gave Bernie a big boost.”

Sanders’ mixed gun record includes voting against legislation requiring more comprehensive background checks while voting to allow firearms on Amtrak. He has also voted for an assault weapons ban and universal background checks.

On Israel, Sanders said that Israel should not be armed by the U.S. early in his career, according to archives from the Vermont Cynic.

“He stood up and said no more guns for Israel in 1972,” said Peter Diamondstone, a longtime Liberty Union candidate who has debated Sanders in seven elections. “That’s certainly not his position now. That’s seriously changed.”

Sanders has said on the campaign trail this summer that he believes Palestinians are entitled to a state of their own, but also expressed support for Israel’s right to defend itself.