WASHINGTON – Republicans and Democrats on Thursday continued bashing each other for the lack of congressional action to combat the Zika virus, after both sides failed to reach agreement on a spending package before leaving town in July for a seven-week recess.

At a Pentagon news conference, President Obama said Thursday that public health officials don't expect "widespread outbreaks" in the U.S., but he said the government is taking the threat "extremely seriously."

"The money we need to fight Zika is rapidly running out," Obama said.

In a letter to Republican leaders, Senate Democrats again suggested cutting their recess short to return to the Capitol to pass new Zika funding. House Speaker Paul Ryan, R-Wis., wrote a newspaper column defending the House-passed Zika spending measure that was blocked by Senate Democrats in July over their objections to policy language dealing with contraception, environmental protections and more.

"Republican congressional leaders should call both the Senate and the House back into session to pass a real and serious response to the burgeoning Zika crisis," more than 40 Democratic senators wrote to Ryan and Senate Majority Leader Mitch McConnell, R-Ky. "The simplest course of action would be to pass the Senate's clean bipartisan compromise on Zika funding by unanimous consent and have the House pass the same bill immediately."

Senate Democrats blamed House Republicans for leaving for the summer recess after they "killed a bipartisan compromise bill that received 89 votes in the Senate," referring to an amendment adopted in the Senate that would have provided $1.1 billion to fight the virus.

Ryan disputed the notion that the $1.1 billion House-passed measure was partisan. "We agreed to the exact level of funding Senate Democrats have supported," he wrote.