Sen. Marco Rubio is an outlier among Republicans when it comes to funding to fight the Zika virus.
And in a new letter Thursday evening, the Florida Republican continued what appears to be an uphill battle to get the full level of assistance pushed by the Obama administration.
"I supported fully funding the fight against Zika with emergency funds to the amount of $1.9 billion, which was calculated by experts in federal public health agencies as the appropriate amount of funds to successfully protect the public health of our country against the imposing threat of Zika," Rubio wrote to the lawmakers negotiating the final bill.
He urged them to "consider these specific requests as you negotiate the final legislation through this conference as quickly as possible."
Rubio's letter asked the 33 members of a House-Senate conference committee, which will attempt to negotiate a final bill, to consider going above and beyond the dollar amount suggested by either the House or Senate.
The House package would provide $622 million while the Senate version would total $1.1 billion.
Health and Human Services Secretary Sylvia Mathews Burwell spoke about the need for assistance in a conference call with governors and public health leaders, according to a statement from HHS.
The agency said that on the call, Centers for Disease Control and Prevention Director Tom Frieden reviewed a plan for responding to cases of the mosquito-borne virus.
The HHS statement said that the draft response plan included input from state and local officials.
It included detailed guidance for states and local jurisdictions on several issues, such as what should be the initial response to local transmission of Zika, how to communicate with the public about a Zika transmission area, "and technical assistance and expanded capacity for mosquito surveillance and control."