The political world has fundamentally changed in the last two and a half weeks.

All the way back in mid-February, Donald Trump brushed aside the coronavirus as “very much under control in the USA”. That was just two days after Bernie Sanders won his breakthrough victory in the Nevada caucuses, putting him on course to a commanding lead as Super Tuesday approached.

This is not the same political country as it was last month

But this is not the same political country it was last month. In the short span of a couple of weeks, American voters have traveled a very long way. If the coronavirus sweeps across the country as the experts predict, that journey will only accelerate, reframing this year’s elections in profound ways.

Tuesday’s primaries confirmed the extraordinary transformation of Joe Biden’s campaign, from almost dead-man-walking to almost dead-certain nominee. There are almost no similar cases of a candidate bouncing into such a wide lead in such a short time.

The last comparable candidate was John Kerry in 2004, moving from single-digits in mid-December to more than 50% of Democratic voters in mid-February. That was after Kerry’s comeback win in Iowa, followed by the swift collapse of an earlier leftwing populist from Vermont: Howard Dean.

Biden’s resurrection is even more dramatic, moving almost as many points in the polls in half the time. It’s true he was never quite as dismally low in the polls as Kerry. But one month ago, the former vice-president was barely ahead of Mike Bloomberg, Elizabeth Warren and Pete Buttigieg.

With his blowout wins in Missouri and Mississippi on Tuesday, Biden has all but ended the Democratic contest. Missouri was essentially a tie between Sanders and Hillary Clinton four years ago. Now Sanders has declined so sharply the news networks could call the race shortly after the polls closed.

In the biggest contest of the night, in the battleground state of Michigan, Sanders once again underperformed compared with 2016, when he struck a blow against the establishment by winning a surprise victory in the upper mid-west.

Sanders’ die-hard supporters have been vocal in their despair, turning their fire variously on the dropout candidates, the party’s elected officials, and the news media. They cannot begin to consider that their candidate’s coalition of diverse, younger voters is nowhere near large enough to win the party’s nomination across the country.

However, the disappointment of the left is only a small part of the story behind Biden’s victory. Democratic voters made it crystal clear in every poll in every state that their overwhelming desire is to beat Trump. The kind of transformative change they were desperately seeking was to kick Trump out of office – even more than restructuring healthcare and free college tuition, which they wholeheartedly support.

Trump’s entirely botched response to the coronavirus pandemic has only intensified this electoral choice. Instead of simply voting for the most electable candidate, Democrats are now voting for the most competent president. In that context, there is vastly more reason to trust a former vice-president than an insurgent outsider.

According to CNN’s exit polls, nearly 60% of Democratic voters in Missouri said they trusted Biden to handle a crisis, compared with about 25% who said they trusted Sanders. In Michigan and Washington state, the numbers were not much better for Bernie.

Other polls underscore how powerful this case is for Biden in his likely general election against Trump. In a recent national poll of registered voters of all parties, Biden beats Trump by 16 points on the question of who would do a better job of handling a crisis, while Sanders is ahead by just six points.

Those numbers landed before the most devastating effects of the coronavirus crisis on communities, patients and the economy. The next two months may not just effectively end the Democratic nomination contest; they may effectively end the entire Trump presidency.

The next two months may not just effectively end the Democratic nomination contest; they may effectively end the entire Trump presidency

For a while on Tuesday night, the only good news for Sanders supporters looked like the screw-up on CNN when the on-air graphics mistakenly suggested that their candidate had won Mississippi.

In reality, Biden had won the state. But as supporters of Britain’s Jeremy Corbyn like to say, Sanders may well have won the argument. Sanders moved Biden further to the left on a publicly funded healthcare option than he and Barack Obama had ever supported in office or on the campaign trail in two elections.

After a few months of the worst of the coronavirus, American support for widely available public healthcare – Medicare for all who want it, as Buttigieg called it – may well attract overwhelming support across the political spectrum.

In the meantime, we can pack up all the old predictions of an extended delegate contest, culminating in that perennial pundit’s dream of a contested or brokered convention. Just a few weeks ago, centrist Democrats were gaming out ways in which the party’s superdelegates could deny Sanders the nomination. Nowadays leftist Democrats are joining forces with the Trump campaign to spread disinformation about Biden’s health.

Biden ignored those malcontents in his victory speech on Tuesday, delivered at the National Constitution Center in Philadelphia without a virus-carrying audience of staffers and supporters. He thanked Sanders’ base for “their tireless energy and their passion”, which is one way to put it. “We share a common goal, and together we’ll defeat Donald Trump,” he explained.

Even more powerfully, Biden cast his own comeback as a model for the whole country. “It’s a comeback for the soul of this nation,” he said. And he cast the response to the coronavirus crisis as a response to three and a half years of living in a constant Trump crisis.

“At this moment, when there’s so much fear in the country and there’s so much fear across the world, we need American leadership,” Biden declared. “We need presidential leadership that’s honest, trusted, truthful and steady.”

Those are lofty standards that used to seem normal. Now Joe Biden has to live by them every day for the next several months of a health crisis we can barely comprehend.