President Donald Trump announced he is halting funding to the World Health Organization on Tuesday, accusing the United Nations agency of "severely mismanaging and covering up the spread of the novel coronavirus" by "parrot(ing)" Chinese government data and not "call(ing) out China's lack of transparency."
His decision has been roundly criticized by lawmakers who challenge its legality, public health experts who say it undermines the global fight against COVID-19, critics who argue Trump is searching for a scapegoat after he was slow to act and similarly praised China's initial response and even the U.S. Chamber of Commerce, a conservative business lobby, which said the timing is wrong.
During his near-daily coronavirus task force press conference on Tuesday, Trump said he was ordering a "halt" to U.S. funding to WHO, the U.N. agency dedicated to global public health that declares a pandemic and organizes resources and shares data to fight outbreaks like Ebola or SARS.
The U.S. provides more funding for WHO each year than any other country, between a static "assessed" contribution around $110 to $115 million and hundreds of millions more for specific initiatives or crises -- reaching between $400 and $500 million in total.
Most of that funding has already been appropriated and provided by the U.S. government across various agencies, including the State Department, the U.S. Agency for International Development and the Department of Health and Human Services.
With Trump's "halt," his administration is working to identify all those programs through which funding flows to WHO and stopping payments, program by program, according to a senior administration official, who said the top-line number should be between $300 and $400 million.
MORE: Despite calls for global cooperation, US and China fight over leading coronavirus responseTop Democrats in Congress said the move is illegal, violating the legislature's power of the purse.
"This decision is dangerous, illegal and will be swiftly challenged," House Speaker Nancy Pelosi said in a statement Wednesday.
A senior Democratic Appropriations Committee aide told ABC News that they see this as "a total political stunt," but that Trump is within his authority here, so long as any frozen money is spent before the end of the fiscal year. Beyond the "assessed" contribution, Congress earmarks around $1 billion for international organizations, but the White House has leeway over how the additional $300 to $400 million that usually goes to WHO is spent.
Still, a senior Democratic House aide told ABC News that lawmakers are reviewing all of their options, including asking for an opinion on the decision's legality from the U.S. Government Accountability Office, an independent, nonpartisan watchdog agency that ruled his hold on Ukraine assistance last year was illegal.
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Beyond the legality, critics have also challenged the rationale for Trump's decision.
Some of his criticisms of WHO are shared by others. The agency said as late as mid-January that there was no evidence of human-to-human transmission of the new virus, only reversing course on that on Jan. 20 when China's National Health Commission announced it could be easily transmitted between people. At that point, there were cases in five countries, in multiple Chinese cities and a mushrooming caseload in Wuhan itself.
WHO "parroted and publicly endorsed the idea that there was not human-to-human transmission happening despite reports and clear evidence to the contrary," Trump said in the Rose Garden. "Had the WHO done its job to get medical experts into China to objectively assess the situation on the ground and to call out China's lack of transparency, the outbreak could have been contained at its source, with very little death."
But at that time, Trump was saying the same thing, tweeting of China's response, "The United States greatly appreciates their efforts and transparency. It will all work out well."
WHO also has limited authority in this regard, unable to send a delegation into a country without that government's permission. With China, it wasn't until February that a WHO team was able to travel and only after its director-general visited Beijing and praised Chinese President Xi Jinping's response like Trump.
Still, WHO's critics say it didn't have to go so far as to endorse China's findings of no human-to-human transmission without conducting its own investigation first.
Trump seemed particularly incensed about WHO's recommendation that countries not implement travel restrictions. The agency said on Jan. 24 that it advises "against the application of any restrictions of international traffic," instead focusing on health screenings at airports and other transportation hubs.
One week after that, despite WHO's recommendation, Trump barred entry to the U.S. for any foreign citizen who had traveled through China in the last 14 days. But even as the virus spread from Asia to Europe and the Middle East, Trump did not take steps domestically or extend his travel restrictions until March.
That lack of action has been at the heart of the criticism now lobbed at Trump -- that he did nothing to prepare the U.S. with the time bought by the early step of restricting travel from China. Amid that criticism, the president has been lashing out at others in recent days, including governors in states hit worst, the news media and now WHO.
Counselor to the president Kellyanne Conway echoed the president's accusations on Wednesday, telling reporters that WHO "knew for a while and they dragged their feet." But she denied that the administration was "scapegoating" the agency.
Asked about Trump's claim that April's warmer weather would bring an end to the coronavirus, she pivoted blame back to WHO.
"The American people should be thrilled about this unprecedented response to this unprecedented crisis," she said. "We're on it, but the WHO was not and frankly others were not."
While Conway told Fox News the halt is "just a pause," the response has been that even a pause would have dangerous effects.
"Halting funding for the World Health Organization during a world health crisis is as dangerous as it sounds. Their work is slowing the spread of COVID-19 and if that work is stopped no other organization can replace them. The world needs WHO now more than ever," tweeted Bill Gates, whose Gates Foundation is a major donor to the agency.
The U.S. Chamber of Commerce agreed, saying in a statement it "supports a reformed but functional World Health Organization, and U.S. leadership and involvement are essential to ensuring its transparency and accountability going forward. However, cutting the WHO’s funding during the COVID-19 pandemic is not in U.S. interests."
That speaks to many concerns that withdrawing U.S. funding actually empowers China and increases its influence at WHO, as it seeks to reshape it and other U.N. agencies in its mold.
"Removing our funding and influence at the WHO will leave a vacuum that China will be more than happy to fill," said Sen. Chris Murphy, a top Democrat on the Senate Foreign Relations Committee.
Even the director of the U.S. Centers for Disease Control and Prevention seemed skeptical, telling ABC News' "Good Morning America" on Wednesday, "The CDC and WHO has had a long history of working together in multiple outbreaks throughout the world as we continue to do in this one, and so we've had a very productive public health relationship. We continue to have that."
For its part, WHO's director-general said he and the organization "regret" Trump's decision, praising the U.S. as a "longstanding and generous friend to WHO, and we hope it will continue to be so." But the agency will work with other partners "to fill any financial gaps we face and to ensure our work continues uninterrupted," he added -- including China.
ABC News' Jordyn Phelps, Trish Turner, Mariam Khan and Christine Theodorou contributed to this report.