Correction appended, Sept. 6, 2016

The U.S. Senate came back on Tuesday from its longest summer recess in 60 years and the first thing it did was fail to pass a bill to address the growing Zika crisis.

The same bill failed twice earlier this summer due to partisan squabbling in an election year. Apparently, the arrival on the mainland of Zika-carrying mosquitos and the local infection thus far of 56 people in Florida alone in the past month has done little to move Washington’s entrenched positions.

“Before the work period, Senate Democrats filibustered funding to combat Zika … not once, but twice,” Senate Majority Leader Mitch McConnell said on the Senate floor. “It’s hard to explain why, despite their own calls for funding, Senate Democrats decided to block a bill that would keep pregnant women and babies safer from Zika.”

Senate Minority Leader Harry Reid responded minutes later: “Democrats pleaded with the Republicans to cut short the seven-week break and return to the Capitol in order to pass emergency Zika funding. Republicans said no, we’re going to stay home some more. And while the Republican Senate insisted on vacation, Zika spread to the mainland here in the United States.”

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Seven months ago, President Obama requested $1.9 billion of emergency funding to address the coming crisis. In May, the Senate voted 89-8 on a $1.1 billion bill. The Republican-controlled House rejected that measure, and instead passed a bill of its own which added in a bunch of controversial ways to pay for the spending, taking money from Obamacare and Planned Parenthood. The measure would also weaken decades-oldpesticide restrictions to combat mosquitoes, a move Democrats oppose. Democrats have decried the provisions as poison pills—indeed they shut down the government in 2013 in order to protect Obamacare from such defunding and nearly shut it down again last year to avoid defunding Planned Parenthood.

Meanwhile, nearly 17,000 Americans have been infected with Zika, including 1,600 pregnant women and thus far 16 babies have been born with the birth defects caused by Zika. The Centers for Disease Control predict by the end of the year 25 percent of Puerto Rico’s population will be infected by Zika. That’s nearly a million people. And as of Sept. 30 the Administration has warned that their current funds available to fight Zika will be used up.

“The cupboard is bare,” CDC Director Thomas Frieden told reporters on Aug. 30. “Basically, we’re out of money, and we need Congress to act to allow us to respond effectively.”

Republicans lost Tuesday’s vote by 52-46; it needed to clear a 60-vote threshold to advance. McConnell’s staff says the conference will now meet to consider how to proceed. Democrats have said they are open to piggybacking the Zika funding—minus the poison-pill provisions—on a massive bill that must pass by Sept. 30 to continue funding the government and avoid a shutdown. But that bill has its own problems, with Reid warning that if Republicans continue to push for a longer funding bill—one that stretches into next spring—the government will shut down just weeks before the election. Democrats, anticipating large advances in the election, are keen to limit GOP influence in next year’s session. The first hundred days are key to a president’s first term and Democrats don’t want to handicap a potential Hillary Clinton presidency.

So, what will happen? Given the pressures faced by vulnerable members—and Republicans have a lot more of those than Democrats this cycle—the issue is likely to find some compromise in the coming weeks. What that will look like depends on how hard Democrats, and vulnerable Republicans, push their leaders and conservative flanks.

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Here’s how that might play out. Sen. Marco Rubio, a Florida Republican, is in a close fight for reelection. His opponent, Democrat Rep. Patrick Murphy, as well as outside groups have been hitting Rubio all summer for his inaction on Zika. Rubio has a narrow lead of 5.7 percentage points, according to an aggregate of Pennsylvania polls done by RealClearPolitics. “Senator Rubio is putting the interests of extreme right-wing groups ahead of the women of Florida,” Sasha Bruce, senior vice president for campaigns and strategy at NARAL, a group that advocates for women’s reproductive rights, said in a statement releasing a television ad by the group hitting Rubio on Zika on Tuesday.

On Tuesday night, Rubio came to the Senate floor to call for passage of the funds, he urged Republicans to consider the Democratic suggestion of rolling the money into the government funding bill.

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“Tonight, for the third time, the minority party, the Democrats in the Senate have blocked more funding to fight this virus. And I want to be frank, at times my own party has not taken the issue seriously enough either,” Rubio said. “My message to both parties and both chambers for this month is simple and straightforward: Zika is not a game. And if you think it is, then you should take your game somewhere else. This issue is about human beings, not political chess pieces, and we have a duty to solve it.”

The election pressures that created the funding impasse may end up spurring a solution too.

Correction: An earlier version of this story included a provision to reverse a House vote that bans the flying of Confederate flags in military cemeteries among the reasons the Zika legislation has stalled. That provision has since been removed.