Criticism of Donald Trump’s response to the coronavirus outbreak is “yet another attempt to impeach the president”, the Fox Business host Trish Regan said on Monday night – even as, on Fox News, so-called Trump-whisperer Tucker Carlson seemed to appeal directly to the president to “tell the truth” about the gathering crisis.

Covid-19 is a respiratory illness transmitted by coughs, sneezes and physical contact that is spreading around the world. It can be fatal, particularly among the elderly and infirm. On Monday, figures from the federal Centers for Disease Control and Prevention (CDC) put the number of US cases at 423, in 35 states and Washington DC and with 19 deaths. Other estimates were higher.

The Trump administration has been criticised for a scattergun response including insufficient testing and cuts to key authorities which handle public health crises.

Trump himself has been criticised for playing down the severity of the outbreak, for making false claims about the nature of the virus and for politicising the problem – in part by repeatedly claiming his opponents and the media are politicising it.

On Fox Business, Regan launched a full-throated defense of Trump. A “chorus of hate”, she said, “being leveled at the president is nearing a crescendo as Democrats blame him and only him for a virus that originated halfway around the world.

“This is yet another attempt to impeach the president and sadly it seems they care very little for any of the destruction they are leaving in their wake. Losses in the stock market, all of this, unfortunately are just part of the political casualties for them.”

Monday saw massive falls in US stock markets, the worst since the 2008 financial crisis.

“You know,” Regan said, “this is a time to be united, not to be pointing fingers, not to be encouraging hate. And yet what do we see? We see the absolute opposite from the left tonight.

“… The hate is boiling over, many in the liberal media using … coronavirus in an attempt to demonise and destroy the president.”

The show then cut to a montage of media figures – and Joe Biden, Trump’s likely challenger in November – criticising the president, some suggesting this could be Trump’s Katrina, a reference to the hurricane which in 2005 devastated both New Orleans and the reputation of George W Bush.

“I see,” Regan said. “This is impeachment all over again. And like with the Mueller investigation, like with Ukrainegate, they don’t care who they hurt.”

Last week, Trump himself drew a parallel between the coronavirus outbreak and his impeachment. In a much-criticised visit to CDC headquarters in Atlanta, Trump said coronavirus tests administered by federal authorities were “all perfect like the letter was perfect, the transcription was perfect”.

That was a reference to a White House version of a call with the Ukrainian president which Trump claims shows he did not apply improper pressure to investigate his political rivals but which most observers say in fact shows the opposite.

But, perhaps reflecting splits on the right of American politics in the face of coronavirus, Carlson took a different tack. On his Monday night show, Carlson, who is known to have Trump’s ear, told viewers coronavirus presented a “very serious problem”.

“People you trust, people you probably voted for, have spent weeks minimising what is clearly a very serious problem,” he said. “‘It’s just partisan politics,’ they say. ‘Calm down. In the end this was just like the flu and people die from that every year. Coronavirus will pass.’”

Trump has repeatedly claimed coronavirus is comparable to or less serious than the common flu – claims rebuffed by public health experts.

“They may not know any better,” Carlson said. “Maybe they’re just not paying attention, or maybe they believe they’re serving some higher cause by shading reality … and there’s an election coming up. Best not to say anything that might help the other side. We get it.

“But they’re wrong … It’s definitely not just the flu.”

Carlson also seemed to address Trump directly, saying that instead of “assuring people that everything will be fine”, it was “better to tell the truth. That is always the surest sign of strength.”

Many observers think a global recession is likely.

On Tuesday morning the Fox News host Laura Ingraham tweeted: “Fact: Some prominent people on the left, trying to frame this is Trump’s Katrina, will be disappointed when US stocks bounce back today. Those aren’t people you want running the country next year.”