The White House said on Monday it needs the US Congress to deliver emergency funding to address the Zika virus, and said redirecting some money set aside for Ebola-related projects would not be enough given the scope of the outbreak.
President Barack Obama has asked Congress for more than $1.8 billion to fight mosquito-borne Zika, which has been linked to birth defects in Brazil and spread to at least 31 other countries and territories, mostly in the Americas.
The money would spur development of tests and vaccines, help states and local governments prepare for and respond to the disease, and help countries and US territories like Puerto Rico that are already grappling with the outbreak.
Several top Republican lawmakers have said the administration should instead draw from $2.7 billion in funds not yet used for public health projects aimed at the Ebola virus.
"The magnitude of the Zika outbreak primarily requires new resources to ensure it is adequately addressed," White House budget director Shaun Donovan said in a letter to Republican Representative Hal Rogers, head of the House Appropriations Committee.
The White House also would like permission from Congress to put unused Ebola money toward Zika projects to "give us the flexibility to respond to Zika needs beyond what we have so far identified," Donovan said in the letter.
Donovan said the administration wants to keep in place "a significant portion" of money pegged to help West Africa recover from a two-year Ebola epidemic that killed more than 11,300 people, and develop public health services to prevent future epidemics.
Much remains unknown about Zika, including whether the virus actually causes microcephaly, a condition marked by unusually small heads that can result in developmental problems.
Brazil said it has confirmed more than 500 cases of microcephaly, and considers most of them to be related to Zika infections in the mothers.
Brazil is investigating more than 3,900 additional suspected cases of microcephaly.