U.S. Democratic presidential candidate Hillary Clinton urged federal lawmakers currently on summer recess back into session to pass a crucial funding bill to combat the Zika virus as she visited a health clinic at the heart of a local outbreak in Miami on Tuesday.

Lawmakers should pass the $1.1 billion bipartisan bill for the mosquito-borne virus, Clinton said, or come up with a new compromise. The funding comes as Florida grapples with at least 21 cases of locally transmitted Zika.

Florida is the first state to confirm local transmission by mosquito bite in the continental United States, but health officials expect additional small outbreaks, particularly in southern U.S. states vulnerable to mosquito-borne disease.

"I am very disappointed that the Congress went on recess before actually agreeing what they would do to put the resources into this fight," Clinton said. "If we pass this critical funding we can develop rapid diagnostic testing and even begin the hard work of developing a vaccine."

The measure stalled after House Republicans attached language that would prevent Zika funding for abortion providers like Planned Parenthood, mainly in Puerto Rico. It would also require the administration to move unused money from President Barack Obama's signature healthcare law to help combat Zika.

Obama had initially asked the Republican-led Congress to approve $1.9 billion in emergency funds.

Several Democratic U.S. senators had sent a letter to Senate Republican Majority Leader Mitch McConnell and Republican House of Representatives Speaker Paul Ryan urging them to summon lawmakers back from their recess to vote on emergency funding.

Florida Republicans Marco Rubio and Gov. Rick Scott have also called on Congress to come back and fund the Zika fight.

Congress has interrupted its own recesses at least eight times since 1998, most recently in 2013 when lawmakers returned early to debate the use of military force in Syria, according to congressional records.

Zika was first detected in Brazil last year and has spread rapidly in the Americas. If contracted by pregnant women, the virus can lead to a rare and devastating birth defect called microcephaly. Brazil has reported more than 1,700 cases of microcephaly.

Clinton made her remarks after touring the Borinquen Health Center in Wynwood, the gentrifying Miami neighborhood in which Florida health officials have reported the Zika cases.

U.S. health officials have urged pregnant women to stay clear of the one square-mile affected area. Clinton's campaign staff gave out cans of mosquito repellent to reporters ahead of the visit.

After meeting doctors, Clinton inspected the leaflets and mosquito nets being handed out to residents and chatted with a pregnant woman who worked in the neighborhood who had gotten back her test results: negative for Zika.

Clinton, speaking to television cameras, said that people should visit a website set up by the federal government that contains Zika information.

"We don't want to unduly alarm people," she said after spelling out the website's address. "We want people to be informed."