To every presidential campaign there is a cycle. There are high points and low points; there are victories and setbacks and perhaps, above all, there is hand-wringing. It is the latter cycle in which Democrats find themselves. Since the 2016 presidential race began, Hillary Clinton has been the assumed Democratic frontrunner, with no apparent political rival to stop her from, this time, grabbing the brass ring. Then along came Senator Bernie Sanders to challenge Clinton from the left.

Before you knew it, Sanders, a 73-year-old socialist from Vermont with a thick Brooklyn accent and a populist, anti-Wall Street and 1% message, was shaking Democrats out of their pro-Clinton slumber. Crowds of more than 20,000 people filled arenas in Los Angeles, Portland and Seattle. Democratic partisans turned out in conservative locales such as New Orleans and Dallas to hear Sanders decry the 1% and pledge radical political change.

Suddenly, the poll numbers began to move. Clinton’s lead in Iowa and New Hampshire (the first two states to cast votes in the presidential race) began to falter and in one New Hampshire poll, Sanders actually is leading. Meanwhile, Clinton’s favourabilities are steadily declining, even among white women, who would seemingly be one of her strongest constituencies. Allegations related to her private email account and a potential federal investigation sent Democratic blood pressure rising.

“Democrats are nearing full-on panic mode,” reported the congressional newspaper, the Hill, over the latest news that seems likely to plague Clinton’s campaign for the foreseeable future. Talk even began of vice-president Joe Biden jumping in the race, even though he has raised no money, has no staff and is polling well behind Clinton. There is, however, only one appropriate reaction to this: meh.

Sanders is only very slightly more likely to be the Democratic standard-bearer than I am. If Biden, who has run two dreadful presidential campaigns (in 1988 and 2008) announces his candidacy he is almost certainly going to be defeated – and embarrassingly so. There is no other Democratic white knight on the horizon (though talk last week began of a possible Al Gore candidacy). Barring some unforeseen event – or perhaps an act of God – Clinton will almost certainly be the Democratic nominee for president in 2016.

The reasons for her dominance are not difficult to figure out. She has raised the most money, she’s secured the most endorsements and quite simply there’s no one else in the party who comes close to rivalling her backing within the party. Her favourability rating among Democrats is well above 80% and she continues to lead Sanders in national polls of party members by 30-plus points.

The key to that support is, perhaps, the most important single constituency within the Democratic party – minority voters. In 2008, African Americans were the key to President Obama’s success in his hard-fought primary win against Clinton. Eight years later, those same voters are solidly in her camp – and neither Sanders, nor Biden, nor any of the other potential challengers for the nomination comes close. Clinton also enjoys a marked advantage among Hispanic voters and among Democratic women.

Facebook Twitter Pinterest Democratic presidential candidate Bernie Sanders is greeted by supporters as he arrives at a campaign event in Indianola, Iowa, on 14 June 2015. Photograph: Jim Young/Reuters

Sanders support can be found primarily among white men and, in particular, the denizens of dark-blue liberal enclaves. The combination of Clinton’s rainbow coalition and Sanders’s more lilywhite liberal supporters also explains his current strong performance in New Hampshire and Iowa, two states not exactly known for their racial diversity. Even in the unlikely chance that Sanders were to prevail in both places, once the Democratic race moves to Nevada, home to a large number of Hispanic voters, and South Carolina, where the Democratic electorate is strongly African American, he will find himself on less hospitable political turf. Quite simply, unless Sanders can make serious inroads among African Americans and Hispanic voters it is nearly impossible to imagine how he could assemble the kind of political coalition necessary to beat Clinton.

Having said all this, Sanders’s support cannot be dismissed so easily. To be sure, his backing is, in some measure, a function of exhaustion with the Clintons, a dash of sexism and a strong perception that the former New York senator is too much of a centrist. That perception is a not indirect result of her vote in 2002 in support of the war in Iraq, a decision that very probably cost her the Democratic nomination in 2008. Yet a closer look at the policy differences between these two candidates shows that Sanders and Clinton are not far apart. Both support same-sex marriage; both want a path to citizenship for undocumented immigrants; both want to expand family and medical leave; both support pay equity; both support the Iran deal; both want to expand voting rights and both want to maintain Obamacare. In some cases, the differences are ones of degree. Sanders calls for a $15 minimum wage; Clinton wants it raised, but hasn’t broadly endorsed the $15 amount. Sanders wants to make public college and university tuition free; Clinton supports that goal for community colleges and just introduced a plan to reduce the costs of higher education.

When I asked the Sanders campaign to identify the major differences between the two candidates a press aide pointed me to a recent TV appearance in which he talked about “differences of opinion” on free trade, the Keystone pipeline, the war in Iraq and the Patriot Act, which he opposed and she supported. These are not insignificant differences, but they’re not major ones either.

Indeed, Sanders argues, “we have to take on the billionaire class and Wall Street. I’m not quite too sure that’s her view.” Yet Clinton has hardly shied away from populist attacks. When she announced her candidacy she criticised the “financial industry” and “multinational corporations” that have “created huge wealth for a few by focusing too much on short-term profit and too little on long-term value, too much on complex trading schemes and stock buy-backs, too little on investments in new businesses, jobs and fair compensation.”

She may not share Sanders’s vehemence on the issue. She has not, for example, called for prosecuting CEOs, as Sanders has, or breaking up big Wall Street banks. She hasn’t spoken of the “grotesque level of inequality” in America or presented it as a moral issue in the same way that Sanders has done. She certainly hasn’t declared to the “billionaire class” that “we have the guts to take you on”.

If one demands a far-left political agenda, a public embrace of socialism and is unwilling to forgive past misdeeds like that Iraq war vote, Sanders is your guy. But it’s hard to imagine, frankly, that most Democrats will parse the issue that closely. If anything, Clinton’s views, more tempered and less aggressive than Sanders’s, are almost certainly a better reflection of where a majority of Democrats would ideologically place themselves.

America finds itself today in a period of extreme political polarisation, in which the differences between the two parties have perhaps rarely – if ever – been starker. Much as liberal Democrats may prefer President Sanders to President Clinton, the latter is certainly far more desirable than President Bush, President Walker or, heaven forbid, President Trump. So in the end the chances that liberals would sit at home on election day if Hillary becomes the nominee are pretty slim.

Indeed, rather than hurting her campaign, Sanders might actually be giving Clinton a boost. Not only is he energising liberals to get more politically involved, but he’s shaking them from political torpor, which, after six years of angry, divisive politics, would not be hard to understand. Moreover, he’s raising the profile of issues, particularly related to income inequality, which plays to Democratic strengths going into the election. His critique of an economic playing field that tilts toward the rich, a political system controlled by the wealthy and of the need for progressive reform that favours middle-class Americans is a message that, rather than undermining Clinton’s candidacy, boosts it.

At a time when Republican candidates are saying things, particularly about women and Hispanic voters, that highlight the most intolerant elements of the party and alienate Republicans from key political constituencies, Sanders is actually reinforcing Clinton’s emerging populist message. It is worth noting that while he has highlighted some of the key policy differences that he has with Clinton, he has also largely refrained from attacking her personally.

In the end, there is, with only a few exceptions, a striking sense of unanimity among Democrats on a host of policy issues. And, in the face of growing Republican extremism, any differences that do exist are likely to be papered over in pursuit of the far larger – and important – liberal goal of keeping the White House in Democratic hands. Bernie Sanders may challenge Clinton on the campaign trail but, paradoxically, he’s more likely than not going to help her make it to the White House.