WASHINGTON (AP) — The Obama administration on Tuesday rejected a Republican suggestion to use money Congress provided to fight the Ebola virus to combat the Zika virus and mosquitoes that spread it.

President Barack Obama is asking Congress for more than $1.8 billion in emergency funding to respond to the Zika virus. There has been no transmission of the virus by mosquitoes within the U.S., but at least 50 travelers have returned home with the infection. At least 16 cases have been confirmed in Florida.

Republican Sen. Roy Blunt, who heads an appropriations subcommittee on health, said the administration has money left over that was allocated to fight Ebola and other infectious diseases.

"So there's no immediate shortage of money for the administration to do what they think needs to be done," Blunt told reporters Tuesday.

But Health and Human Services Secretary Sylvia Burwell said she and other administration officials "believe we need to finish the job in terms of Ebola" and focus separately on Zika.

"We want to do both of them and we are going to do both," Burwell said after she and other top officials briefed congressional leaders late Tuesday on efforts to combat Zika.

Burwell, who was set to testify before Congress this week on the administration's funding request, called the briefing "a great opportunity to talk about the (Zika) disease and ... the facts about what we do know and don't know about the disease."

While experts don't expect large outbreaks in the continental U.S., the emergency funding would help officials prepare for any local transmission as spring and summer approach. The administration is seeking the Zika money separately from the regular budget for the next fiscal year that Obama submitted to Congress on Tuesday.

"The urgency is learning what we can to do to fight it," Burwell said, adding that the disease had already shown up in Puerto Rico. "We need to put those things in place now."

Most of the money would go to improving laboratory testing capacity, education and establishing rapid response teams. About $250 million of assistance would be directed specifically to Puerto Rico through extra federal funding for health services, and $200 million would go toward research and commercialization of new vaccines and diagnostic tests.

About $335 million would go to the U.S. Agency for International Development to help affected countries train health workers and help pregnant women gain access to mosquito repellant.