Former US Secretary of State Hillary Rodham Clinton at the Clinton Global Initiative in New York City, on Sept. 23, 2014.
Spencer Platt/Pool/Getty

Can anyone stop Hillary Clinton?

Updated

Hillary Clinton will not clear the field.

Even as a cadre of the Democratic Party’s greatest minds and deepest wallets convene in a hotel ballroom in New York City to plot Clinton’s domination of the 2016 presidential nomination, a field of credible challengers is beginning to take shape.

The question is whether they will be the party’s next Dennis Kuciniches – idealistic, but ultimately doomed candidates – or Barack Obamas. So far, Clinton-backers don’t seem too nervous.

On Thursday, former senator Jim Webb became the first person to officially throw his hat in the ring when he announced an exploratory committee. The decorated Vietnam veteran with populist swagger and an anti-interventionist streak has already excited some progressives.

Related: Is Jim Webb 2016’s Barack Obama?

Like Obama, Webb would differentiate himself from Clinton on foreign policy, and especially the Iraq War, which he famously opposed. Unlike Obama, Webb would challenge Clinton from the political center, where some think Clinton is even more vulnerable than on her left.

Webb has yet to build a political infrastructure, apparently giving little heads up to allies about his impending announcement. Still, it was not a complete surprise. He’s made one trip each to Iowa and New Hampshire, and told reporters in recent months that he was seriously considering a bid.

On the other side of the ideological spectrum is Vermont Sen. Bernie Sanders, who is so liberal he’s not even a Democrat (yet), but an independent. Sanders has not made a final decision, but recently brought aboard top-flight Democratic strategist Tad Devine.

On Wednesday night, Sanders’ would-be campaign team huddled for several hours at a private home on Capitol Hill in Washington to go over the structure of the primary process and the feasibility of a run, a source familiar with the meeting told msnbc.

The group included Devine and business partner Mark Longabaugh, who ran then-Sen. Bill Bradley’s 2000 presidential campaign against Al Gore in New Hampshire, which could serve as a model for any insurgent run against Clinton. Several other strategists were present as well, including one involved in Obama’s 2008 bid.

“He’s looking at it very seriously, asking that all the questions that he needs to ask about a real campaign,” the source said of Sanders, who expects to make a decision “sooner rather than later.”

Sanders may struggle to be taken seriously by the mainstream press, but he starts with nearly $5 million in his political coffers and a national fundraising base that includes 750,000 campaign fundraising contacts.

Related: Hillary Clinton: GOP ‘abdication’ forced Obama’s hand on immigration

The senator insists he’s not interested in running a mere protest campaign, and those around him say he would only do it if he could mount a serious campaign. That means raising and spending at least $50 million in the early states, which would pay for television advertising, a full field operation in Iowa and New Hampshire, a more modest field presence in later states, a headquarters staff, and the resources to allow Sanders to travel and campaign.

Sanders has visited the early states several times already, and has another trip to Iowa planned for mid-December.

Despite major policy differences, supporters of both Webb and Sanders cast their candidates in some similar ways. Americans are sick and tired of politics as usual, both camps say, and are ready to embrace a nontraditional politician who will speak to their economic needs and anxiety.

Martin O’Malley, the third candidate not named Clinton almost certain to get into the race, would cast himself differently. O’Malley would tout his executive experience as both governor of Maryland and mayor of Baltimore, in contrast to the Senate careers of Clinton, Warner, and Sanders. And while the other three are in their late sixties or early seventies, O’Malley is almost two decades younger.

He worked harder than anyone to support fellow Democrats in key states in 2014, and recently hired a former Clinton adviser as policy director of his nascent presidential effort. While some Democrats blamed O’Malley for the defeat of his hand-picked replacement, Anthony Brown, those familiar with his thinking say he’s pressing ahead. “As he sees it, it doesn’t really change anything,” one source said.

So are any of these men capable of being the next Barack Obama?

Bill Burton, who witnessed Obama’s rise from inside as press secretary for the 2008 presidential campaign, isn’t convinced. “Even though President Obama was a new senator and serious underdog, he was still one of the most famous Democrats in the country when he announced in 2007. None of these other Democrats have that kind of profile or even the access to the kind of infrastructure he was able to build so quickly,” he said.

Indeed, while Clinton skeptics are often quick to point out that Obama blindsided Clinton, the then-senator’s rise was foreseeable in late 2006. At roughly this point in the 2008 presidential election cycle, Obama was already emerging as a clear threat. A CNN poll released in early November had the young senator trailing Clinton by just 11 points, and Pew dubbed him the “leading rival” to Clinton. Then-Sen. John Edwards was also attracting a sizable portion of the vote.

Clinton was a frontrunner then, but not the same way she is now. Current surveys consistently show Clinton leading by 50 percentage points or more. And the would-be candidate in second place, Vice President Joe Biden, is unlikely to run if Clinton does.

“The polls are overwhelming about what Democratic voters want, it’s not even close,” said former Pennsylvania Gov. Ed Rendell, who supporters Clinton. “No one is going to overcome that … It wasn’t like this last time.”

In addition to being an exceptional candidate and skilled fundraiser, Obama had one other big thing going for him that the likely batch of Democrats this time to do not: His biography.

It’s not a great time to be a white man in Democratic politics if you have White House ambitions, since many voters want to make history again by electing a woman. And being a minority also gives candidates a natural base of support.

Another former governor who has thrown his support behind Clinton, Ohio’s Ted Strickland, who now leads the political arm of the Center for American Progress (CAP), said that while he thinks the other potential candidates have something to offer, Clinton remains the strongest.

“But that does not mean that I don’t appreciate Bernie Sanders, Sen. Elizabeth Warren, Gov. Martin O’Malley – a lot of other important leaders in the Democratic Party who can contribute to the development of an agenda to move our country toward a more just, egalitarian set of policies,” he told msnbc Wednesday at a CAP conference. “We need strong progressive voices.”

Even among liberals, there seems to be little room at the moment for a challenger. Exit polls from this month’s election show that 83% of Democrats think Clinton would make a good president, while 88% of “solid liberals” view her favorably, according to a recent Pew poll. “Despite all the talk about a ‘yearning’ for a more liberal candidate from the Democratic base, we see no evidence – at least at this point – that liberals are unhappy with Hillary Clinton,” the nonpartisan Cook Political Report wrote.

That could change, however. Democracy for America, the group that grew out of Howard Dean’s presidential campaign, asked for their members’ opinions on 2016 this week and found twice as many wanted Warren as Clinton, who also finished slightly behind Sanders.

All of these non-Clinton Democrats are largely unknown outside their home states. That’s a challenge for them in the short run, but a big opportunity in the long run, because it means they have plenty of room to improve their standings.

In Iowa and New Hampshire, voters are quick to tell reporters that they favor a competitive nominating process, suggesting the other candidates will be given a serious look.

And the landscape is favorable this cycle in New Hampshire. A competitive Republican primary means many independents are likely to vote in the GOP contest, leaving behind a more liberal pool of voters in the Democratic primary.

Meanwhile, other candidates could still get in, though it’s unclear who. Warren finished at the top of the DFA poll, but has repeatedly said she’s not running and has given no signals to the contrary. Massachusetts Gov. Deval Patrick is also popular, but seems intent on getting out of politics for now.

“The only profile of a candidate who would have a chance, except Hillary Clinton, would be someone like a big state governor,” said Rendell, noting they could raise the necessary funds for a run right out of the gate.

New York Gov. Andrew Cuomo has long harbored national ambitions, but is loyal to the Clinton family, and was politically damaged in his reelection bid this year.

California Gov. Jerry Brown, on the other hand, fought a bruising primary against Bill Clinton in 1992 and is a bit of a maverick in his party. He’s also sitting on a massive $21 million war chest, and is still raising more money, despite easily winning re-election this month (he says he wants to use the money to push ballot measures in 2016).

“You never say never with Jerry Brown,” Rendell said.

Regardless, it’s clear Clinton will have a real competitive process on her hand. There will be no coronation. 

Bernie Sanders, Hillary Clinton, Jim Webb and Martin O'Malley

Can anyone stop Hillary Clinton?

Updated