Kevin Lamarque / Reuters

Two months ago, the Obama administration asked for roughly $1.9 billion in emergency funding to combat the Zika virus. Public-health officials were eager to get money for vaccine research and more. “We are hopeful that Congress will recognize the urgency of this request and act quickly on it,” White House Press Secretary Josh Earnest said at a February briefing, accompanied by health-agency officials. “This sort of falls in the category of things that shouldn’t break down along party lines.”

But break down it did. House Republicans, who’d need to sign off on the spending, told the White House to repurpose money appropriated to fight Ebola. The administration maintained Ebola funds wouldn’t cut it, but nevertheless announced it would divert $600 million while it waited on more from Congress.

Latest from Politics

From Politician to Indie Filmmaker

Now, even top public-health officials seem willing to join the political fight. At a press briefing on Monday, they reminded reporters how much work on Zika still needs to be done—and just how much money they’ll need to do it. “I don’t have what I need right now,” said Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, referring to funding for his agency. He added: “When the president asked for $1.9 billion, we needed $1.9 billion.” When Fauci last spoke to White House reporters in February, along with the principal deputy director of the Centers for Disease Control and Prevention, Anne Schuchat, the two officials didn’t wade into the funding battle much at all. On Monday, Fauci was particularly vocal about the urgency of the funding request, insisting—as other agency directors did earlier this month—that the full $1.9 billion is needed.

The Republican-controlled Congress, though, isn’t convinced the administration needs all the funding it’s requested, at least not right away. House Speaker Paul Ryan said late last month that the government already has enough money to fight Zika. According to a report in The Washington Post last week, Senate Republicans said they’d get to the funding question in ongoing budget talks. “We’re going to continue to talk about what we’re going to do to get us to a better place in the future,” said Senator Roy Blunt, the chairman of the subcommittee that handles health-agency funding. The House, often the source of budget stalling, could present even more difficulties, although Tom Cole, Blunt’s counterpart in the lower chamber, said Monday he believes more money will come. “I think the administration has made the appropriate first move responding to Congress’s request” on shifting Ebola funds, Cole said. But “now I think the ball is clearly in Congress’s court to sit down and put together a package. Whether it needs to be $1.9 billion right now I think is the question.” He said he’ll be meeting with leadership this week to discuss the funding.

In recent weeks, officials’ concerns about Zika have been amplified by a steady stream of unsettling discoveries about the virus’s reach and effects. The World Health Organization formally declared for the first time last week that Zika causes the birth defect microcephaly and the autoimmune condition Guillain-Barré syndrome, and researchers are investigating possible links between Zika and brain and spinal-cord infections. Though there haven’t been any locally acquired cases in the continental United States—and just 346 travel-related cases—the coming summer months are a concern. The virus is particularly worrisome for cities like Miami and Houston, which have high population densities and high temperatures and are home to Zika’s host mosquito, as Adrienne LaFrance reported earlier this week.

“Now I think the ball is clearly in Congress’s court to sit down and put together a package.”What scientists are learning about Zika “is not reassuring,” Schuchat said Monday. Researchers have been most concerned in recent months about Zika’s effect on pregnant women, because of the connection to microcephaly, a condition in which babies are born with abnormally small heads. Schuchat noted the pregnancy complications could be even broader than what officials once thought: Zika has been linked to premature births and eye conditions in infants. Women at every stage of pregnancy may be vulnerable to the virus’s effects; previously, health officials thought only first-trimester pregnancies could be affected.

The virus’s range is also difficult to predict. Two of its relatives, dengue and chikungunya, haven’t led to many locally transmitted cases in the continental United States, which hypothetically should be reassuring. But Schuchat said officials can’t make any assumptions. “Everything we look at with this virus seems to be a bit scarier than we initially thought,” she said.

As officials learn more about the virus, Fauci said, he “can’t imagine” Congress not coming through with more funds. The alternative would be too damaging. “If we reach the point where the stopgap money runs out … we’d have to start raiding other accounts and very important research on other diseases is going to suffer, and suffer badly,” Fauci said. Not only that, but Schuchat said the necessary “long-term work” on Zika—such as multiyear studies on children—can’t be done “if additional resources aren’t coming.”

Even $1.9 billion may not be enough. Although he didn’t mention it at Monday’s briefing, Fauci suggested months ago that the amount was only an estimate. “We put in a proposal for what we thought was necessary to do what we need to do,” he said in February. “And if it turns out that we get further into it and there’s a lot more, then I think there will be another request.”