Virginia Gov. Ralph Northam said on CNN's "State of the Union" Sunday that President Trump is "delusional" for suggesting there's enough coronavirus testing capacity for states to reopen, echoing the concerns of a number of governors who have called for a national testing strategy.

Why it matters: Public health experts say that testing must be doubled or even tripled from current levels in order to allow for a safe, partial reopening of the U.S. economy. Trump is pushing to have some states partially reopen by May 1.

Yes, but: While the number of tests conducted in the U.S. has ramped up significantly since the start of the outbreak, the figures have plateaued over the last week and fall far short of what experts say is needed.

Governors say there are shortages of key testing ingredients like swabs and reagents that are preventing their states from meeting demand.

Some labs also have excess testing capacity, but aren’t being sent samples from the providers collecting them due to poor coordination.

What they're saying: Trump tweeted on Sunday, "Just like I was right on Ventilators (our Country is now the “King of Ventilators”, other countries are calling asking for help-we will!), I am right on testing. Governors must be able to step up and get the job done. We will be with you ALL THE WAY!"

Maryland Gov. Larry Hogan (R) said on CNN: "I've talked to governors on both sides of the aisle nearly every single day ... 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."

Michigan Gov. Gretchen Whitmer (D) said on CNN that "it would really be incredibly helpful if the federal government would use the Defense Production Act to start making these swabs and reagents so we can improve testing."

"At the end of the day, you know, we governors are doing the best we can with what we've got," she added.

Ohio Gov. Mike DeWine (R) said on NBC's "Meet the Press" that he hopes the FDA might approve a slightly different testing formula to allow companies to ramp up testing, since there's a "worldwide shortage of some of the materials that go into this."