All eyes are on New York's new Mayor

The city is being led by a liberal for the first time in a generation, and the Democrats – especially Hillary Clinton - will be watching closely

Uphill battle: New York’s snowstorm is the first test of Bill de Blasio’s term as Mayor

Last Friday, less than 48 hours after being sworn in, Bill de Blasio was coping with his first test as New York's new Democratic mayor – the fearsome winter storm that has plunged the US north-east into deep freeze.

"Hizzonor", not surprisingly, was most visibly on the front lines, shovelling away snow outside his modest Brooklyn row house in front of the watching cameras. In these parts, there's nothing like bad weather to prove the adage that all politics is local. For a mayor, nothing spells trouble like a mishandled storm and unploughed city streets. But sooner rather than later, New York's snow will melt. A more pertinent question is: will the new brand of politics de Blasio represents prove more durable?

For years, all the talk in US politics has been about the Tea Party and the conservatives' tightening grip on the Republican party, and the risk faced by moderates of being "primaried": challenged in a primary election by a more radical opponent from within their own party. But Bill de Blasio is a symbol of similar stirrings among Democrats. After years of quiet, dating back to when Bill Clinton imposed his centrist "New Democrat" philosophy in the early 1990s, the populist left is once again on the move. One sign was the election of the Wall Street critic and consumer rights advocate Elizabeth Warren to Ted Kennedy's old Senate seat in next door Massachusetts last year. Another was the advent of New York's first avowedly liberal Mayor in a generation.

Discontent with Barack Obama is not confined to a Republican right that viscerally loathes the man. The left has long since fallen out of love with this President as well. Many feel betrayed by his cautious centrist policies, the absence of action to match his soaring rhetoric, his failure to take on the citadels of wealth and privilege and stand up for the little man, the "ordinary guy" who features in every Obama speech.

There's resentment at Obamacare, of course, but not just on account of its disastrous roll-out (although the website healthcare.gov does now finally seem to be working better). Americans who oppose the President's overhaul of the bloated, over-expensive US healthcare system that left 45 million uninsured are not just Republicans who regard the whole thing as a socialist takeover of the country. They also include a significant minority of Democrats who believe the new law doesn't go far enough in the direction of a government-run single-payer system that covers everyone, or "Medicare for all".

But the real complaint of the left runs deeper. Obama was elected as a Democrat committed to change. But during his five years in power, the gap between rich and poor has widened, not narrowed. Not a single top financial or bank executive has been charged for misconduct in the 2008 crash – yet millions have lost their homes. It may not be Obama's fault, but Congress cannot even find the will to raise the minimum wage, or extend unemployment benefits for those who, through no fault of their own, fail to find a job.

And then you listen to de Blasio on the steps of City Hall, delivering his "Tale of Two Cities" inauguration speech on New Year's Day, talking again and again of the Dickensian condition of the near 50 per cent of the city's population that lives at or close to the official poverty line, and promising to tax the rich to finance better daycare and early education for the children of the less fortunate.

It may, of course, all end in tears. The post-crash Occupy Wall Street movement fizzled, while the last spell of unabashed soak-the-rich policies in New York, in the late 1960s and early Seventies, ended in the humiliation of near-bankruptcy in 1975. One thing, though, is sure. Bill de Blasio will be the most closely watched mayor in the US, and what happens in New York will have an real impact on national politics. In fact, if de Blasio's inauguration ceremony is any indication, it already is.

A year from now, we should know the answer to the question that dominates every political calculation: will Hillary run in 2016? The presumption is that she will (though personally I am yet to be wholly convinced), and that conventional wisdom was only reinforced last Wednesday.

Michael Bloomberg and Rudy Giuliani, the previous two mayors, were sworn in by mere judges. For Bill de Blasio, however, a former president did the honours, accompanied by his wife. Certainly, the Clinton couple had plenty of reason to be in attendance. Bill is now based in New York City, while Hillary was a senator for the state. Indeed, de Blasio, having served in her husband's first administration, managed her successful campaign in 2000. But Bill himself didn't have to administer the oath – and when it comes to politics, no gesture by a Clinton is ever accidental.

If Hillary were to run, she would obviously be a formidable candidate. But for the left, she too is suspect, on account of her vote in favour of the Iraq invasion, and her ties to Wall Street. After she decided to make a second White House bid, the last thing she needs is to be "primaried" by a serious, more liberal Democratic challenger. She would surely prevail, but only at the cost of a split within the party that would harm her chances in the general election – just as the split in the Republican party doomed Mitt Romney last time.

Seen from that perspective, the very public Clinton cosy-up with de Blasio makes absolute sense. The possible future president has symbolically aligned herself with a current hero of the party's left wing, creating a bridge between the New Democrat centrists and an impatient left that is once again on the march. In doing so, she can only have reduced the risk of that primary challenge.

As for new Mayor, he gets a popular ex-president's seal of approval, whose impact will be felt long after this weekend's snows have melted.