The U.S. coronavirus crisis took a sharp political turn on Friday as President Donald Trump lashed out at four Democratic governors over their handling of the pandemic after having conceded that states bear ultimate control of restrictions to contain the outbreak.

The Republican president targeted three swing states critical to his re-election bid — Michigan, Minnesota and Virginia — where his conservative loyalists have mounted pressure campaigns challenging those governors' stay-at-home orders.

Amplifying a theme that his supporters have trumpeted this week in street protests at the state capitals of Lansing, St. Paul, and Richmond, Trump issued a series of matching Twitter posts touting the slogans: "LIBERATE MICHIGAN!" "LIBERATE MINNESOTA!" and "LIBERATE VIRGINIA!"

At a news conference on Friday, Trump again criticized the handling of some states' coronavirus mitigation measures as Virginia "too tough."

Asked if certain states — Michigan, Minnesota and Virginia — should lift their stay-at-home orders, Trump said: "No, but I think elements of what they've done are too much."

A banner of U.S. President Trump on an American flag is held above a crowd demanding the state's Stay at Home order be lifted during a 'Liberate Minnesota' protest in St. Paul, Minn., on Friday. (Evan Frost/Minnesota Public Radio via AP)

Michigan has become a particular focus of agitation to relax physical-distancing rules that rank among the strictest in the nation after Gov. Gretchen Whitmer, widely seen as a potential running mate for presumed Democratic presidential candidate Joe Biden, extended them through the end of April.

Protesters defying the restrictions from the steps of the state Capitol on Wednesday shouted "lock her up," a chant that was a staple of Trump's campaign rallies and originally referred to his 2016 Democratic rival, Hillary Clinton.

Whitmer said on Friday she was hopeful her state, which suffered one of the country's fastest-growing coronavirus infection rates, can begin to restart parts of its economy on May 1. But she urged doing so cautiously to avoid reigniting the outbreak just as it appeared to be getting under control.

Responding to Trump's critique later in the day, she said, "We will re-engage our economy when it's safe," adding: "The last thing I want to do is to have a second wave here."

'Passing the buck'

Trump also took renewed aim at one of his favourite political foils, New York Gov. Andrew Cuomo, in a tweet suggesting that his state, the U.S. epicentre of the outbreak, had asked for too much assistance that was never fully used.

At his televised daily news briefing, Cuomo shot back saying Trump should "maybe get up and go to work" instead of watching TV, and accused the president of favouring the airline industry and business cronies in a recent bailout package that left little for the states.

Cuomo said Friday that he needed federal help to ramp up testing for the coronavirus and to reopen his economy, and criticized the White House, accusing Trump of bailing on a comprehensive testing strategy because it was 'too complicated."

WATCH | Cuomo criticizes Trump over lack of federal aid:

New York Gov. Andrew Cuomo says U.S. states can't reopen their economies until coronavirus testing is ramped up and more funding comes from Washington. 2:30

He said he needs federal funding to significantly ramp up testing capacity and to fill a $10 to $15 billion US budget shortfall that is hampering the state's ability to fund such efforts on its own. He criticized the aid packages passed by Congress to date for a lack of funds to hard-hit states like New York.

"Is there any funding so I can do these things that you want us to do? No," Cuomo told a daily briefing. "That is passing the buck without passing the bucks."

Reopening U.S.

Trump, who played down the coronavirus threat in the early stages, had pressed earlier to restart idled businesses as soon as May 1, declaring "total" authority to do so while branding governors who resisted his approach as "mutineers."

In the end he acknowledged it was up to the governors to decide when and how to relax the stay-at-home orders they themselves had imposed since last month, presenting his guidelines as recommendations.

On Thursday, Trump unveiled new federal guidelines for a staggered, three-stage process by which states could gradually lift restrictions on businesses and social life as the pandemic ebbed.

WATCH | Trump outlines three-phase plan to reopen some states:

U.S. President Donald Trump announced federal guidelines on Thursday for some states described as being in "good shape" to start easing up on shutdown measures and reopening economies. 4:46

While the guidelines called for a phased-in, science-based strategy in keeping with the advice of leading health authorities, the plan hinges on widespread testing that many governors say remains beyond reach due to failings of the Trump administration to ever launch such an effort.

Trump has insisted it was up to the states to ramp up such testing.

The United States has reported more coronavirus cases than any other country, with nearly 690,000 known infections as of Friday, including more than 35,300 deaths.