With less than a month to go until the Iowa caucuses that open the Democratic primaries Bernie Sanders seems to be gaining momentum. A recent poll has put him in the lead in this state – the winner of which has gone on to win the Democratic nomination since 1992. While other polls have shown Joe Biden or Pete Buttigieg in the lead – or even a three-way tie – it seems everything is still to play for.

When Sanders decided to run for the presidency again many were inclined to dismiss him. His better than expected performance in the 2016 primaries was put down by many to protest votes against Hillary Clinton. Elizabeth Warren seemed more able to bridge the gap between the Democratic establishment and progressive activists. Biden seemed an establishment figure able to compete effectively with Sanders for white working-class voters.

Initially these predictions seemed to be borne out. Yet Warren is fading in the polls and the gap between Biden and Sanders is narrowing. Sanders seems to sense victory might be in reach.

In recent days Sanders has stepped up his criticism of other candidates. In the wake of the Iran strikes, Sanders attacked Biden for his past support for the Iraq war – and has continued to do so. He also criticised Biden’s past opposition to busing to integrate schools – perhaps a risky move given it seems Sanders himself has also done so in the past.

Meanwhile, Warren has complained Sanders sent out activists to “trash” her by arguing she only really appeals to highly educated voters who vote Democrat anyway. While this is still fairly gentlemanly stuff for a primary, the Sanders camp does seem to be stepping up its offensive game.

A win – or even a razor thin loss – in Iowa would set Sanders up nicely for the New Hampshire primary on 11 February. The state is already friendly ground for Sanders. Its overwhelmingly white demographics offset Sander’s disadvantage among black voters. It neighbours his home state of Vermont, and he won it in 2016 kickstarting his insurgent run against Clinton. Sanders has also recently shaken up his campaign team in the state apparently feeling it had been under-performing.

Two strong performances in a row could even help Sanders overcome his Achilles heel – that relatively weak support he attracts among black voters. Currently Biden has an overwhelming lead among older black voters, and Sanders has only a narrow advantage among black millennial voters.

A lot of this has to do with not just Biden’s proximity to Obama and strong links to influential African-American organisations but black voters’ perception that Biden is a safer pair of hands electorally. Currently this gives Biden a strong lead in a number of key Southern states. But nothing succeeds like success. The more Sanders wins the more he will seem like a winner, potentially helping to overcome, or at least narrow, Biden’s advantage.

Should Sanders win the nomination he stands a good chance of winning the presidency. While large swathes of the Democratic establishment, and voters, would not be thrilled by his candidacy, their hatred of Trump would ensure they coalesced behind him. Even Michael Bloomberg has sworn off running a third-party campaign if Sanders becomes the nominee, having previously hinted he might do so.

Republican leaning independents who the Democrats hope to win over – mainly white suburban voters who swung Democrat in the 2018 midterms giving them control of the House of Representatives – might be put off. However, Sanders’ popularity in Rust Belt states would help to bring working-class Obama-Trump swing voters back into the fold. Black voter turnout – key for any Democratic candidate and vital if the Democrats hope to make inroads in the Sun Belt states like Arizona, Florida, and South Carolina – could be boosted by choosing a black vice-president as running mate.

Attacks on Sanders as a socialist, a radical, and un-American may not stick as much as Republicans hope – for much the same reason that Trump’s many grotesque scandals failed to sink him. For both their presence on the political fringe and willingness to say unpopular things has become a strange asset – a sign of authenticity at a time when distrust of politicians is rampant. Alongside distrust of the political establishment comes distrust of the mainstream media – negative reporting will be more easily brushed off than it once was. Indeed, being openly hated by people their supporters hate only bolsters their base. Finally, at a time when many Americans feel they are approaching a crisis, many are prepared to give radicalism a go.

Some Democrat supporters, including people not inclined to support Sanders, are beginning to talk him up as an insurgent who could win. The idea of “the Reagan of the left” i.e. someone on the party fringe who unexpectedly captures the nomination and manages to appeal to sections of the electorate otherwise unreachable for the party, was floated by Bloomberg columnist Noah Smith.

There would be an ironic historical echo if an unpopular incumbent involved in a brush with Iran lost in 2020. It is difficult to think of a president more different from the pious, gentle, and conscientious Jimmy Carter than Trump, though. Indeed, in many ways Sanders’ candidacy resembles Carter’s. At a time when the political establishment has never seemed more corrupt, apparent distance from it and perceived moral clarity could appeal to many.

Of course, Sanders may run into much the same problems as Carter if he wins. The global economy is due a recession. As for policy Sanders would actually control should he become president this does not seem like a welcoming time for America to adopt an idealistic foreign policy.

Still, if Sanders becomes the nominee, then it is not impossible he becomes president.