Bernie Sanders steamrollered through the Nevada primary and Donald Trump played down the coronavirus threat. Who’s up and who’s down this week in US politics?

Best week: Bernie Sanders

Facebook Twitter Pinterest Bernie Sanders supporters. Photograph: Erik S Lesser/EPA

The leftwing senator from Vermont’s landslide victory in Nevada forced Democratic and media doubters to admit he was now the man to beat (even the day before the New York Times was still calling him the “nominal” frontrunner). But heavy lies the crown – with his new status came the avalanche of attacks from opponents that Sanders sceptics have long warned the self-proclaimed democratic socialist would face if he ever began to lead the pack.

His “honeymoon” to Moscow, unwise articles he wrote for an underground zine in the 60s and 70s about cancer, orgasms and rape fantasies … Indeed, Sanders fanned the flames himself this week with typically unapologetic comments about Fidel Castro, telling CBS News he was “opposed to the authoritarian nature of Cuba” but adding: “He had a massive literacy program. Is that a bad thing? Even though Fidel Castro did it?” There will be much more of this if Sanders’ success continues with a strong showing in South Carolina tomorrow and victory on Super Tuesday, 3 March.

Good week: Joe Biden

Facebook Twitter Pinterest Joe Biden: might be back. Photograph: Gerald Herbert/AP

Whisper it, but is Biden back? Democratic centrists will eventually have to coalesce around someone to take on Sanders, and after flirting with Pete Buttigieg, Mike Bloomberg and Amy Klobuchar, they may end up concluding that the former vice-president – for all his faults – looks the strongest. He was more focused and aggressive at the debate in South Carolina on Tuesday night, and employed some amusing self-deprecation at one point when he gave way to the moderator: “Why am I stopping? No one else stops. It’s my Catholic school training.” Relying on his firewall of African American support, Biden has solidified his lead in South Carolina and can reasonably hope for a strong victory there on Saturday that might reboot his campaign. He can expect to scoop up a fair number of delegates on Super Tuesday too, particularly in Texas and North Carolina, although Sanders is increasingly leaving him for dust in California. Can he stage a comeback? Cutting out the questionable stories about being arrested in South Africa might help.

Not a great week: Mike Bloomberg

Facebook Twitter Pinterest Mike Bloomberg: not the best at social media. Photograph: Nate Billings/AP

Bloomberg had a better debate this week, but his social media tactics came under fire after his team posted a controversial set of satirical tweets featuring false comments supposedly made by Sanders about various dictators. It wasn’t his first offence – many objected to the misleadingly edited video his team had put out after the debate in Nevada – and the Sanders tweets were deleted. “It’s the embracing of a cynical outlook: ‘Lol nothing matters’,” Whitney Phillips of Syracuse University told the Guardian. “It’s leaning into nihilism.” Bloomberg’s national poll ratings have flatlined since his disastrous first debate performance – he remains in third place behind Biden and Sanders – and he has dipped back below Elizabeth Warren and Pete Buttigieg too in the crucial Super Tuesday state of California, when he enters the race proper.

Bad week: Donald Trump

Facebook Twitter Pinterest Donald Trump: ready for coronavirus to go away. Photograph: Chip Somodevilla/Getty Images

The US Centers for Disease Control and Prevention warned this week that the coronavirus Covid-19 could could cause “severe disruption” to the lives of ordinary Americans, adding: “It’s not so much a question of if this will happen any more, but rather more exactly when this will happen, and how many people in this country will have severe illness.” Donald Trump didn’t like that. On a trip to India earlier that day he had already told reporters that the coronavirus was “very well under control in our country” and “is going to go away”. He later hit out at the media for “doing everything possible to make the Caronavirus [sic] look as bad as possible, including panicking markets, if possible”.

That last element seemed key – an economic slowdown caused by the virus could seriously damage Trump’s chances of re-election, and the stock market is his favourite measure of his own success. The day after a less-than-reassuring press conference in which Trump put the vice-president, Mike Pence, in charge of the anti-virus effort, the Dow had its worst ever daily drop and the S&P 500 posted its largest fall since August 2011.

Worst week: Mike Pence

Facebook Twitter Pinterest Mike Pence: maybe not the man for the job. Photograph: Carlos Barría/Reuters

Well, would you want to head up the coronavirus response? Such a poisoned chalice is the vice-president’s new job that there was even speculation Trump could eventually use it as a pretext for dropping Pence from the 2020 ticket – perhaps replacing him with a telegenic woman such as the former UN ambassador Nikki Haley.

Not to worry, though, Pence is “really very expert at the field” of healthcare, as Trump told his press conference on Wednesday.

So expert that he notoriously wrote on his website in 2000: “Despite the hysteria from the political class and the media, smoking doesn’t kill.” And as governor of the midwestern state of Indiana, he faced heavy criticism for his handling of the situation when the state experienced the worst HIV crisis in its history.