Senate Democrats on Tuesday blocked a Republican proposal to provide $1.1 billion to fight the Zika virus, faulting the GOP for packing the measure with restrictions on Planned Parenthood money and changes to policies on pesticide spraying.

The nearly party-line 52-48 vote Tuesday left the Senate short of the 60 votes required to advance the measure. What happens next is unclear, though neither side is looking forward to leaving Washington next for a seven-week vacation without having acted to address the health threat. 

Zika is spread mainly by a tropical mosquito and is causing an epidemic in Latin America and the Caribbean. The virus can cause horrible birth defects and is likely to spread further this summer.

Democrats pressed to resume negotiations while Republicans insisted, for now at least, that the measure negotiated by House and Senate Republicans is the best the Obama administration is going to get. The administration has requested $1.9 billion in emergency funds in February.

"There's not going to be another opportunity to deal with this in the near future," promised No. 2 Senate Republican John Cornyn of Texas.

The House-Senate measure matches the $1.1 billion measure that passed the Senate last month on a sweeping vote, but Democrats oppose a handful of provisions designed to mollify GOP conservatives in the House and the attachment of companion spending cuts to defray its cost.

Democrats particularly oppose a provision that restricts the use of $95 million worth of federal grants to provide services such as birth control to women in Puerto Rico threatened by the virus. Democrats charged that the restrictions were targeted at Planned Parenthood, a group loathed by many anti-abortion Republicans.

Democrats argue that Republicans used the bill to push their ideology. In addition to the limits on Planned Parenthood, the bill would lift restrictions on pesticide spraying that is opposed by environmentalists.

Even as Democrats pressed for compromise, they crowed that Republicans controlling Congress would soon reconsider.

"They come back with their tail between their legs saying `Let's pass something,"' said Sen. Charles Schumer, D-N.Y.

President Barack Obama requested $1.9 billion back in February but Republicans controlling Congress were slow to act, instead forcing the administration to redirect more than $500 million in unspent Ebola-fighting funds to combat Zika.