U.S. Senate negotiators on Wednesday tried to reach a deal to provide more than $1 billion to battle the Zika virus that is feared will creep north into the United States with the onset of warmer weather, which breeds mosquitoes that could carry the disease.

Senior Senate Democratic aides said details were still being worked out, but votes could come by next week on whether to approve the new money.

In February, President Barack Obama requested $1.9 billion in emergency funds, but Republicans balked, with some arguing that $1.1 billion is more in line with what is needed. Many Republicans also want any Zika funds to be offset with spending cuts elsewhere.

These are among the details that still have to be worked out, according to aides.

Republican Senator Roy Blunt from Missouri and Democratic Senator Patty Murray from Washington, the two senior senators on an appropriations panel that oversees healthcare spending, have been trying to hammer out a deal.

An aide to Murray said in a statement: “Senator Murray is having conversations with Chairman Blunt and others about the path forward on emergency funding to respond to Zika."

The aide said Murray still supports Obama's $1.9 billion request.

Amid congressional inaction, the Obama administration shifted $589 million to help federal agencies prepare for Zika. Most of that money came from a fund to fight the Ebola virus and will have to be replenished, according to officials.

Senator Marco Rubio, however, is one Republican pushing for both immediate, emergency funding and longer-term money to be made available starting on Oct. 1 to battle the disease that can cause severe brain deformities in babies born of infected mothers and other illnesses.

"This is going to be an ongoing issue beyond this year," Rubio said, adding, "We need to jump on it now."

There are fears that Rubio's home state of Florida could be the first place in the continental United States to get hit hard by Zika because of its tropical climate.

"For the first time, I've seen high-level conversations about a way forward here in the Senate and that's a positive development," Rubio said in a brief hallway interview with Reuters.

Republicans in the House of Representatives are still deeply divided over new funding for Zika, according to two senior aides.