WASHINGTON — Federal money left over from the largely successful fight against Ebola will now go to combating the growing threat of the Zika virus, the Obama administration said Wednesday.

Most of the $589 million would be devoted to the Centers for Disease Control and Prevention for research on the virus and Zika-related birth defects, as well as the creation of response teams to limit its spread. The National Institutes of Health would continue research into a vaccine and the US Agency for International Development would intensify efforts to fight the virus overseas.

Researchers fear Zika causes microcephaly, a serious birth defect in which a baby’s head is too small.

President Obama had asked for about $1.9 billion in emergency money to fight Zika but the request has stalled in the GOP-controlled Congress. White House budget chief Shaun Donovan and Health and Human Services Secretary Sylvia M. Burwell said the administration still needs the full request to fight Zika and maintain vigilance on Ebola.

While the administration has acknowledged that substantial Ebola funding is left over, it has already committed much of it to helping at least 30 other countries prevent, detect, and respond to future outbreaks and epidemics.

Republicans on Capitol Hill had suggested the administration consider reshuffling existing funds and said they are open to paying the money back in future legislation if it’s needed for Ebola or some other purposes.

Associated Press