Interviews with more than a dozen economists, many of whom are veterans of past presidential administrations, reveal broad consensus on the building blocks the economy needs — but does not yet have — to begin the slow process of restoring normalcy in the American economy.

That includes widespread agreement that the United States desperately needs more testing for the virus in order to give policymakers the first key piece of evidence they need to determine how fast the virus is spreading and when it might be safe for people to return to work.

Without more testing, “there’s no way that you could set a time limit on when you could open up the economy,” said Simon Mongey, a University of Chicago economist who is among the authors of a new study that found that rapid deployment of randomized testing for the virus could reduce its health and economic damage.

“It’s going to have to depend on being able to identify people that have the coronavirus, understanding how readily those people can transmit the disease to others and then kind of appropriately isolating people that are contagious,” Mr. Mongey said.