Washington — Governors facing rising pressure to begin reviving economies that were brought to a halt because of the coronavirus pandemic are finding themselves at odds with President Trump, who asserts the country's testing capacity is sufficient for them to begin easing restrictions on businesses and activities.

Mr. Trump and Vice President Mike Pence spent the weekend defending the number of tests being conducted, with the president saying the onus is on governors to increase testing.

"States, not the Federal Government, should be doing the Testing - But we will work with the Governors and get it done. This is easy compared to the fast production of thousands of complex Ventilators!" Mr. Trump tweeted Monday, claiming "Do Nothing Democrats" spent the month of March raising concerns about ventilators for patients battling COVID-19, the disease caused by the coronavirus.

... “Testing, Testing, Testing,” again playing a very dangerous political game. States, not the Federal Government, should be doing the Testing - But we will work with the Governors and get it done. This is easy compared to the fast production of thousands of complex Ventilators! — Donald J. Trump (@realDonaldTrump) April 20, 2020

But governors say that a major hurdle to opening up their states again is a lack of testing supplies, such as swabs and chemical reagents, that has prevented them from boosting their testing capacity, as well as an inadequate national testing strategy.

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A shortage of tests is the "number one problem in America and has been from the beginning of this crisis," Maryland Governor Larry Hogan, a Republican, told CNN in an interview Sunday.

"The administration, I think, is trying to ramp up testing. They are doing some things with respect to private labs," Hogan said. "But to try to push this off to say that the governors have plenty of testing and they should just get to work on testing — somehow we aren't doing our job — is just absolutely false."

Governors, he added, have been "pushing and fighting and clawing to get more tests" from the federal government and private labs in the U.S. and worldwide.

Hogan was able to secure 500,000 coronavirus tests from South Korea, his spokesman Mike Ricci said Monday.

Ohio Governor Mike DeWine, a Republican, told NBC's "Meet the Press" on Sunday he could "double, maybe even triple testing in Ohio virtually overnight" if the Food and Drug Administration (FDA) would help the state with securing reagents.

"We have a shortage, worldwide shortage, of some of the materials that go into this. So, we really need help," he said. "If anybody in the FDA is watching, this would really take our capacity up, literally Chuck, overnight."

Massachusetts Governor Charlie Baker, a Republican, also called on the federal government to step in.

"I certainly believe that the more guidance and especially the ability to put the foot on the accelerator with respect to advancements in testing, everything associated with testing ultimately has to be approved by the [Centers for Disease Control] and the FDA," he said on "Face the Nation."

Mr. Trump's assertions that there was enough testing in the U.S. to allow states to begin loosening restrictions was rebuffed as "delusional" by Virginia Governor Ralph Northam, a Democrat who said his state has been fighting to secure personal protective equipment and other supplies as part of its response to the coronavirus epidemic.

"We've been fighting for testing. It's not a straightforward test," he told CNN. "We don't even have enough swabs, believe it or not, and we're ramping that up. But for the national level to say that we have what we need and really to have no guidance to the state levels is just irresponsible, because we're not there yet."

Public health experts say mass testing is a key condition for gradually reopening the U.S. economy while staving off another outbreak, and the Trump administration seems to acknowledge the role it can play with helping states secure necessary supplies for test kits.

Mr. Trump on Sunday told reporters at the White House that he is planning to invoke his authority under the Defense Production Act to compel an unnamed U.S. company to produce 20 million more testing swabs per month. Pence was also set to hold a call with governors Monday "to review what more they can do and do together to develop locally tailored testing strategies," the president said.

The U.S. is currently conducting 150,000 tests daily and has done 4 million tests overall, Pence said, and he urged governors to activate all labs in their states to ramp up testing.

But Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, said that while the government is conducting roughly 1.5 to 2 million tests weekly, that level needs to double or triple.

"We need a partnership between the federal government and the local people, including the governors, to help them get to things that they maybe not have any access to," he said.