More than 40 U.S. Senate Democrats sent a letter Monday to Republican Majority Leader Mitch McConnell, demanding immediate passage of $1.9 billion in emergency funds to fight the Zika virus.
The Democratic lawmakers accuse Republicans of failing to act even after 800 Americans, including 89 pregnant women, have been infected.
"It would be shortsighted and dangerous for Congress not to act quickly to give the administration the resources it needs to fully fight the ZIka virus and protect Americans," according to the letter.
The Obama administration said last week it will use $510 million in unspent funds for fighting Ebola to tackle Zika.
But Democrats say public health officials should not have to choose between the two diseases, noting that 13 new Ebola cases have cropped up in West Africa over the last month.
Republican leaders say they want more information about the president's emergency request for Zika, and that they plan to approve some funding. However, they have been vague on when and how much.
U.S. health officials confirmed last week that Zika is a cause of birth defects, including microcephaly — a condition in which babies are born with abnormally small heads.
Experts warn pregnant women or those planning to get pregnant to avoid travel to Latin American countries with large Zika outbreaks.