Senate Democrats on Thursday voted to maintain their weeks-long filibuster of Zika-fighting money, sending Congress home for a seven-week recess without any additional funding for vaccine research or mosquito eradication.

Democrats said Republicans forced them to block the deal by offering too little funding with too many strings attached, but the impasse means President Obama will have to make do without any more money as health officials warn of a looming Zika breakout in the U.S.

No local transmission has been detected in the states, though mosquitoes are spreading the infection in Puerto Rico. More than 1,300 travel-related cases have been reported nationwide.

The stalemate belies a productive July for Congress, which this week has passed bipartisan bills on fighting opioid addiction and on labeling genetically modified crops.

The bipartisan spirit dissipated Thursday as furious Senate Republicans blasted Democrats for delaying the Zika money and holding up a spending bill to fund active-duty troops and the Pentagon.

“How in the world do you refuse to take up legislation that its only purpose is to defend this nation, which is under assault?” said Sen. John McCain, Arizona Republican.

Republicans fell five votes shy of the 60 needed to overcome a filibuster of the defense bill.

Democrats said the Pentagon was getting a boost but feared Republicans would pare back later on bills to fund domestic needs. Blocking the defense bill now gives them leverage to argue for domestic spending increases later, Democrats hope.

It’s the latest hiccup in the annual spending process. Republicans kicked off the year by failing to pass a budget. Now, the spending bills that are supposed to carry out the blueprint have stalled.

If the standoff continues, it will force Congress in September to pass a stopgap bill extending 2016 spending levels into fiscal year 2017, which begins Oct. 1.

House Speaker Paul D. Ryan, Wisconsin Republican, wasn’t prepared to concede that Thursday.

“I just don’t think it’s right at this stage to say we’re done with appropriations, we’re going to move on,” Mr. Ryan said at his weekly press conference.

The spending fights aside, the House has made major headway. On Thursday, lawmakers cleared a bipartisan bill clarifying what kind of labeling needs to be attached to genetically modified crops.

That bipartisan 306-117 vote was followed by more partisan votes in favor of bills punishing Iran for its human rights record and a bill to fund the Interior Department and Environmental Protection Agency. Each of those partisan bills faces a veto threat from the White House.

Without additional funding to fight Zika, the White House will have to stretch some $589 million it shifted earlier this year.

Republicans say less than 20 percent of that money has been spent, leaving plenty to use over the next weeks.

The top Republicans on the House and Senate spending committees fired off a letter telling the White House to ransack other funds if it runs out of money before September, when lawmakers return to Capitol Hill.

“If Senate Democrats continue to block consideration of Zika legislation, we urge you to aggressively use funds already available to mount a strong defense against the virus,” the lawmakers said in a letter to Mr. Obama.

Senate Minority Leader Harry Reid, Nevada Democrat, said his troops had no choice but to block the Republican plan, which included provisions preventing Planned Parenthood from being part of birth control efforts and rolling back clean water rules in a rush to kill Zika-carrying mosquitoes.

He said party leaders should have reopened the deal before the Republican National Convention next week in Cleveland.

“They want to go. They want to go listen to Donald Trump,” Mr. McConnell said of the presumptive Republican presidential nominee.

Sen. John Cornyn, Texas Republican, said Democrats seemed more desperate to protect their political allies than babies born to Zika-infected mothers.

“Unfortunately, they made the wrong choice,” he said. “They failed the test.”