Former President Barack Obama on Wednesday criticized the lack of a "robust system of testing" for coronavirus in the US.

"Social distancing bends the curve...But in order to shift off current policies, the key will be a robust system of testing and monitoring – something we have yet to put in place nationwide," Obama tweeted.

The US is well behind other nations in terms of testing for coronavirus per capita.

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Former President Barack Obama on Wednesday offered veiled criticism of the Trump administration's failure to establish a "robust system of testing" for the novel coronavirus.

"Social distancing bends the curve and relieves some pressure on our heroic medical professionals. But in order to shift off current policies, the key will be a robust system of testing and monitoring — something we have yet to put in place nationwide," Obama said in a tweet.

The former commander-in-chief's comments echo recent recommendations from the World Health Organization, which has said that social distancing is "buying time" but must be paired with widespread testing in order to defeat the pandemic.

The US has struggled to implement testing on a broad scale, which is largely due to early stumbles by the federal government in preparing for and responding to the novel coronavirus. The Centers for Disease Control and Prevention sent out faulty test kits in February, and the US has been behind the curve ever since.

Dr. Anthony Fauci, the US's top expert on infectious disease, in March told House lawmakers the US must admit it's "failing" in terms of testing for the virus.

More recently, a sobering report from the inspector general of the Department of Health and Human Services warned of recurring delays and issues with testing at US hospitals, as well as severe shortages of supplies.

President Donald Trump has scoffed at questions from reporters about issues with testing, and often made misleading comments about the availability of tests.

On March 6, for example, Trump said "anybody" who needs a test could get one. That was not true then, and remained false as of Wednesday.

Trump on Tuesday also falsely said the US is outpacing other countries in terms of testing.

"We've performed 1.87 million tests to date. So that's 1 million, 870 thousand — million tests. Think of that: 1,870,000 tests to date. And now we're performing them at a level that nobody has ever seen before," Trump said at the daily White House press briefing on coronavirus.

But with a population of roughly 327 million people, and less than 2 million tests conducted, this places the US far behind other countries in terms of testing per capita.

Trump has at times sought to blame the Obama administration over testing failures, stating he inherited a broken system, event though the novel coronavirus only emerged several months ago.

A majority of Americans (52%) said Obama would be a better leader than Trump during the coronavirus pandemic, compared to just 38% who said the same about Trump, a Politico-Morning Consult poll released on Wednesday found.

As of Wednesday morning, there were over 12,000 reported coronavirus deaths in the US, and roughly 400,000 confirmed cases of the virus.