In modern presidential politics, the second time isn't usually the charm.

Hillary Clinton, Mitt Romney and John McCain all suffered general election defeats in their second runs for the White House. The last candidate who successfully converted a second try at the presidency into a victory was George H.W. Bush in 1988 – and he was a sitting vice president in a bygone era that accepted succession and admired experience.

In this new age of media saturation, instant gratification and continual political disruptiveness, new and fresh is preferable to tested and known. The insurgent is defined as the outsider who flouts the rules because she or he hasn't even had the opportunity to play by them before. The fresh face makes for the more compelling story because it is less familiar and more revelatory about the given moment. This fascination with the political neophyte inevitably leads to more generous and flattering news coverage for the said individual.

In 2016, this role was filled by Bernie Sanders in the Democratic primary. The Vermont independent who began his campaign with a majority of Democrats having no opinion of him steadily became the populist folk hero that galvanized a new era of proud progressivism.

Now, as he inches toward another bid in the coming months – the 77-year-old said he'll "probably run" if he determines himself to be the best candidate to defeat President Donald Trump – Sanders begins a potential race in a dramatically different position than he was for his 2016 pursuit.

Then, he was dismissed as a hopeless gadfly. Now, he's a proven vote-getter and the unofficial leader of the left. Then, his avowed socialism looked like a fringe ideology. Now many of his positions have been adopted by his would-be rivals. Then, he began the primary race polling in single digits. Now, nearly every poll shows him vying for front-runner status with former Vice President Joe Biden.

But along with those tangible advantages of having run before comes the other end of the sharp double-edged sword.

In 2020, Sanders would no longer be the stated underdog. Without the element of surprise, it will be difficult for him to morph into the insurgent. Because his candidacy would immediately be taken seriously, it would instantly earn far more scrutiny than it did last go-round.

In 2015, Sanders' share of news coverage far exceeded his share in national polls. The senator "benefited from increasing news coverage that was more positive than Clinton received," wrote political science professors John Sides, Michael Tesler and Lynn Vavreck in "Identity Crisis," a new book that re-evaluates the 2016 presidential campaign. "Just as it did for Trump, media coverage brought Sanders to a wider audience and helped spur his long climb in the polls by conveying the familiar tale of the surprisingly successful underdog."

What's more is Sanders would (likely) not have the benefit of running against a highly polarizing figure in Clinton. Instead, he'd face a fleet of ambitious young talent with binders full of progressive credentials. One or more will almost certainly experience a break-out moment of their own.

So the conundrum for Bernie is how he can recreate the magic of his first run – and whether it's even possible. It's a question Sanders himself has raised in conversations with aides over the past year as he campaigned across the country for progressive candidates with mixed results .

Some of his close allies and admirers are privately questioning the potency of a second run with so many Democratic aspirants eager to hop off the bench, as are some who worked for him.

"Do I think he can rekindle the magic of 2016? No, he's going to have to reinvent the wheel," says Michael Ceraso, Sanders' 2016 deputy director in New Hampshire, who later left the campaign after a disagreement with manager Jeff Weaver. "The biggest challenge I see for him is the talent pool. There's not just one Democrat that's Hillary anymore. There's Kamala [Harris], there's Cory [Booker], there's Joe Biden. And people already know what [Bernie's] gonna say. They're going to wonder what Kamala's going to say in New Hampshire, what Cory's going to say in New Hampshire."

Another battleground state Democratic staffer who was contacted by a Sanders aide in September to move over to the team demurred, hoping for an eventual slot on a rival campaign. On Sanders, this staffer says: "The water's going to be a lot colder this time," just due to the sheer number of other options that are emerging.

From Sanders' team's point of view, Bernie would still begin with advantages any candidate would envy: the largest established fundraising base with the ability to raise around $250 million from a small donor army, existing organizations in all 50 states, the proven ability to draw large crowds, nearly universal name identification.

"Regardless of what ultimately happens, I think much of the race frames around him," says Mark Longabaugh, a senior Sanders adviser.

With an anticipated Democratic field that could include more than a dozen viable candidates – many of them progressives – Sanders appears prepared to play the authenticity card: that he was there first on the litany of progressive issues from "Medicare-for-all" to a $15 minimum wage to free college tuition – and that he took the risk and fought for them when they weren't as popular and made them mainstream.

The final chapter of his new book, "Where We Go From Here: Two Years in the Resistance," alludes to this distinction.

"Interestingly, a few years ago," Sanders writes, "almost no candidates for office campaigned on 'Medicare-for-all.'"

One could almost imagine this line being deployed on a debate stage.

"You're gonna have a lot of Johnny-come-latelys," says Chuck Rocha, another Sanders adviser. "In the tumultuous times we live in, people are looking for a rock in a river. Bernie Sanders has been that stalwart rock."

Robert Becker, Sanders' Iowa director in 2016, spent the last several months in Florida working on a midterm campaign. But when he recently stepped back into a Des Moines coffee shop, the locals took that as a sign.

"Folks were just downright giddy," he says. "Their thinking was that because I was back in Des Moines, it meant that Bernie was going to run."

Becker was simply returning home, but he says he stands ready for the call to work the first-in-the-nation caucus state again for the socialist wunderkind and points to the story as emblematic of how solid the Sanders coalition remains.

He says a second Sanders campaign would remain an insurgent one because of the core beliefs that he's never wavered from.

"The freshness is, he's still sort of the trendsetter, he's ahead of the curve on issues," Becker says. "We're tickled to death that all these people have been following his lead on 'Medicare-for-all' and a $15 dollar minimum wage. Bernie got in the race in '16 and stuck in the fight. And this isn't gonna be a head-to-head race. It's 30 ways."

Sanders' isn't expected to move on a campaign until after the new year, taking the customary time to huddle with family and feel out advisers. But it would be more of a shock if he didn't turn the ignition, given his unique position in a party he doesn't even formally belong to.

Sure, Clinton, Romney and McCain all came up short on the ultimate prize in their second runs, but Longabaugh pointedly notes that each captured their party's nomination.

But he reaches back decades for an analogy to Sanders' situation and comes up with an unlikely comparison that will make conservatives smirk.

"Ronald Reagan, in 1976, ran a very ideological race as a figure reshaping the Republican Party. He was bested but continued to run and ended up securing the nomination and winning in 1980," he says. "I think there is a parallel. Bernie has reshaped the Democratic Party now as much as Reagan reshaped the Republican Party in that period."