As far back as 2009, the 2016 primary election was seen by Democratic party insiders as a coronation for Hillary Clinton . She was well-known and well-connected with an impressive resume and plenty of experience running for president before. Defeating any opponents would be nothing more than a formality.

Clinton would never have anticipated that barely a fortnight before the Iowa caucus – a crucial battleground for any candidate – she would be trailing to a self-described socialist who looks like Doc Brown and talks like Seinfeld's George Steinbrenner.

But despite all the odds, Vermont Senator Bernie Sanders has captured the zeitgeist of the Democratic primary.

This comes in spite of Sanders not being a Democrat, having run as an Independent for his entire political career. As a hardcore liberal, Sanders is far to the left of Clinton on a plethora of economic issues. But for perhaps the first time in his career, he has become the unlikely populist candidate.

His popularity flies in the face of conventional wisdom. He's not a slick or particularly charming politician. On television he looks prickly and agitated, and he's reluctant to go off-message to address the news of the day. But polling in recent months has shown him in a stronger candidate in the general election against the Republicans. Clinton may beat Donald Trump by seven points, but Sanders beats him by 13 .

Bernie Sanders. (AAP)

But that's maybe because Republicans are laying off Sanders because they want to face him in the general. Unlike Clinton, Sanders' past has gone by relatively unscrutinised. His favourability ratings may drop once voters find out about his honeymoon in the USSR, or his perceived intentions to raise taxes on the middle class.

He's also struggling to gain media coverage despite having considerably more supporters than Trump . But a vocal group of supporters on social media, especially Reddit, mean Sanders can bypass the power of the conventional press to get his policies out there.

Sanders has launched an ambitious agenda in his presidential run, with policies far beyond the scale of Clinton's. They include introducing government-funded universal health care, breaking up the big banks and making tuition at public universities free. His plans make Clinton's policies look decidedly unimpressive.

The problem is, Sanders hasn't revealed how he will pay for this. Less than three weeks from the first vote and the senator is yet to release his tax plan. It's hard to believe Sanders isn't just running out the clock with such little time to spare. It's a canny political move from the man positioning himself as the anti-politician.

But while Iowa and New Hampshire may seem like the most important states in the primary, Sanders' real challenge comes later. Because just like Sanders' supporters, Iowa and New Hampshire are overwhelmingly white states.

Compare that to the next primary states. In South Carolina, where a majority of primary voters are black, Clinton has a 36-point lead in the latest poll. In the heavily Hispanic Nevada electorate, Clinton has a 23-point lead.

But wins by Sanders in Iowa and New Hampshire can change that. In 2008 Clinton had a wide lead in the national polls but fast lost ground against Barack Obama after he won Iowa.

The other question is whether Sanders' supporters will actually turn up to vote. Despite being the oldest candidate in the field, his voter base is strongest in the under 30s, a group notorious for not showing up on election day.

Do you think Bernie Sanders can be president? Yes 3467 No 3049