A $1.1 billion dollar proposal to support anti-Zika virus efforts at federal health agencies failed to advance in the Senate, opening up the possibility no funds will be authorized before September. 

The bill had passed the House last week, almost entirely on Republican support. Though the legislation was supposed to be crafted based on a conference committee after the two chambers of Congress approved different amounts of Zika funding earlier in the year, Democrats refused to sign off on the committee’s version, which relies on reprioritizing $750 million from other health agencies, including $540 million from a fund to help U.S. territories set up health insurance exchanges and $100 million from HHS’s administrative funds. It also contains amendments blocking funding to Planned Parenthood and making changes to the Clean Water Act, both of which Democrats have labeled “poison pills.”

The legislation needed 60 votes to end debate in the Senate, but only received 52. Senate Majority Leader Mitch McConnell, R-Ky., questioned why Democrats would oppose the bill, which matches the level of funding the Senate approved earlier this year.

“Democrats have tried to claim they weren’t involved in the negotiations over this legislation, but they were from beginning to end—and the House agreed to the funding level that Democrats supported unanimously,” McConnell said. “Democrats have tried to trot out the ‘War on Women’ playbook, but this legislation actually provides more resources for women’s health services—through hospitals, health departments, community health centers, and other public programs.”

Speaking at a press conference after the vote, McConnell repeatedly said there would be no changes made to the bill. In a procedural move, McConnell voted against the legislation, allowing him to bring up for consideration again at a later date.

The Senate Democratic leadership—Minority Leader Harry Reid of Nevada, Dick Durbin of Illinois, and Chuck Schumer of New York—called on Republican leaders to scrap the current bill and restart conference talks.

“Already, four children have been born in the United States with birth defects, while four other pregnancies with evidence of birth defects have been lost,” the Democratic leaders wrote. “From the first moments it became apparent that the Zika virus would present a major public health threat to American women and families, Democrats have been clear that a swift and sufficient response would be necessary. We are fully committed to working with you to negotiate a response that sufficiently rises to this challenge. To that end we are ready and willing to immediately join you in a new round of negotiations on a truly effective, bipartisan package.”

The current congressional calendar leaves little time to reach a compromise. The Senate will be recessed from July 1 through 5 and then will only have another eight scheduled session days before taking an unusually long break from July 18 through Sept. 8.

Agencies which have been working on a Zika vaccine urged Congress to put some funding package together quickly.

“If we don’t get new money, we won’t be able to do things at a pace that is necessary and appropriate to the urgency of this threat,” Anthony S. Fauci, MD,  director of the National Institute of Allergy and Infectious Diseases, said to the New York Times.

The timing matters because mosquitoes in states along the Gulf of Mexico, along with Arizona and California, may already be transmitting the Zika virus to people.

“The most direct way to determine if Zika virus transmission has begun would be if local, county, or state health officials were to undertake programs of active surveillance in which people living in potentially at risk communities would be asked to provide a blood sample to look for evidence of recent or past exposure to Zika,” wrote Peter Hoetz, MD, PhD, dean of the National School of Tropical Medicine at Baylor College of Medicine.  “Such studies, however, require funds to hire new staff or divert existing staff from current activities. Unfortunately, in the absence of new funding from the U.S. Congress, it’s unclear whether significant numbers of such studies are underway.”