US President Donald Trump proposed guidelines on Thursday under which US state governors could act to revive the US economy from its coronavirus shutdown in a staggered, three-stage process.Speaking at his daily briefing on the coronavirus, which has killed more than 32,600 Americans in a matter of weeks, Trump argued that a prolonged shutdown could be deeply harmful to the US economy and society. "We are not opening all at once, but one careful step at a time," Trump told reporters, without himself providing details on his guidelines."A prolonged lockdown combined with a forced economic depression would inflict an immense and wide-ranging toll on public health," Trump said, adding it could lead to a sharp rise in drug abuse, alcohol abuse, suicide, heart disease."The new federal guidelines recommend that states record a 14-day "downward trajectory" in coronavirus cases before beginning a three-phase process of re-opening.The document lays out Trump's plan for opening businesses in states across the country that have been ravaged by the pandemic and its economic impact even though the responsibility for such decisions lies with state, not federal, authorities.Before states re-open, hospitals should have a "robust testing program" that includes antibody testing in place for healthcare workers, the guidelines say.States should have the ability to set up screening and testing sites for people with symptoms and as well as contact tracing capabilities, and healthcare facilities should be able to supply personal protective gear independently and handle surges if COVID-19 cases increase again.The document says the recommendations are "implementable on a statewide or county-by-county basis at governors' discretion." Trump has tussled with governors over who has the ultimate authority to mandate a re-opening of states' economies.In the first phase of re-opening, the guidelines say groups of more than 10 people should be avoided if appropriate distancing measures are not practical. Non-essential travel should be minimized, telework should be encouraged, and common areas in offices closed.Schools remain closed in phase 1, but large venues such as movies theaters, restaurants, stadiums, and places of worship can open with "strict physical distancing protocols."Hospitals, which have been hit hard by the health crisis, may resume elective surgeries, which are critical to their income, and gyms can re-open with new protocols. Bars should remain closed, it said.In the second phase, applicable to states and regions with "no evidence of a rebound" in cases, the guidelines recommend groups of more than 50 be avoided where social distancing is not practical. Non-essential travel can resume, while schools and youth camps can reconvene and bars with "diminished standing-room occupancy" may re-open.Phase three includes unrestricted staffing of workplaces.A White House official described the guidelines as conservative and noted that they had been agreed to by the top doctors on the president's coronavirus task force.Trump is pushing to get the US economy going again after the coronavirus shutdown left millions of Americans jobless. More than 20 million people have filed for unemployment in the US in the past month and over 90% of the country have been under stay-at-home orders.Trump said on Wednesday some states with low numbers of infections will be ready to resume economic activity sooner than those hard hit by the highly contagious virus.The White House official said that each governor will be able to look to the recommendations as a guide."They are layered," the official said, adding they were approved by medical experts on the White House coronavirus task force: infectious disease expert Anthony Fauci, task force coordinator Deborah Birx and Robert Redfield, director of the Centers for Disease Control and Prevention.