WASHINGTON (Reuters) - A bipartisan group of senators will soon offer a proposal for more funding to fight a Zika outbreak spreading rapidly through the Americas, Senate Appropriations Committee Chairman Thad Cochran said on Thursday. Democrats and Obama administration officials have urged the Republican-controlled Congress to grant nearly $1.9 billion in emergency funds to combat Zika, a virus borne by mosquitoes that can cause microcephaly, a rare birth defect. But many Republicans have said they need more information from the administration before approving the measure.  In a temporary fix, the White House said earlier this month it would reprogram $589 million of allocated funds, but said this would be insufficient to deal with the threat. Cochran, speaking at an appropriations committee meeting, did not say how much funding would be in the proposal. The Republican said it would supplement the White House reallocation. “We recognize that there is an urgency associated with the threat,” Cochran said. “This proposal will provide new resources ... It is my expectation that this proposal will be offered to an appropriations measure on the Senate floor in the near future.” Senator Barbara Mikulski, the senior Democrat on the panel, said lawmakers must act before July 1. “We are in a race against the clock, we are in a race with the mosquitoes and right now I would say that the mosquitoes are winning.” Zika was first detected in Brazil last year and linked to a spike in the birth defect microcephaly, a condition defined by unusually small heads that can hamper development, as well as the rare autoimmune disorder Guillain-Barre syndrome in adults. U.S. health officials say local outbreaks are possible in the continental United States once the weather warms, particularly in southern states such as Florida. But mosquitoes that carry the virus could spread further north. Cochran said it had been difficult to obtain the information necessary to thoroughly evaluate the Obama administration’s Zika funding request, a complaint also raised by Republicans in the House of Representatives.  Several senators, including Democrat Patty Murray and Republican Roy Blunt, are working on the proposal, Cochran said. Blunt told the panel that he and Murray were largely in agreement and he looked forward to working on the matter over the next few days. “I believe we are closing in on a number that is the right number,” he said, without elaborating. 