A U.S. officer conducts an interview with a passenger arriving from West Africa in this handout picture taken at Washington Dulles International Airport October 16, 2014. (Handout/Reuters)

Lawmakers voiced skepticism on Friday about Obama administration assurances that government measures are likely to succeed in protecting the United States, and U.S. soldiers overseas, from further spread of the Ebola virus.

Rep. Darrell Issa (R-Calif.), who chairs the House Oversight and Government Reform Committee, characterized the administration’s response to the disease so far as “bumbling.”

“I think we all know that the system is not yet refined to where we could say it is working properly,” he said during a hearing on government management of the disease.

Issa and other members of Congress questioned measures the administration had taken to prepare for a possible pandemic before Ebola appeared in U.S. hospitals, and their recommendations to health-care workers and the public since then.

The hearing came the morning after a New York doctor who recently returned from West Africa was confirmed to have Ebola. He was the fourth person to be diagnosed with the disease in the United States.

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Officials from the Department of Health and Human Services and the Defense Department detailed plans for preventing the spread of Ebola at home and among U.S. troops being sent to the disease’s epicenter in West Africa.

Earlier this year, President Obama ordered up to 4,000 U.S. soldiers be sent to West Africa to train local health workers, build treatment facilities and help coordinate the international response to the disease.

But lawmakers pointed out that the government’s own guidelines for quarantine, travel safety and the protection of medical workers appeared to have evolved in the weeks since Ebola was first diagnosed in a U.S. hospital.

“Lately, when a government agency comes before this committee, especially, and tells me, ‘There’s nothing to worry about. We got this,’ that’s when I start to worry,” said Rep. Stephen F. Lynch (D-Mass.).

Nicole Lurie, a senior official at the Department of Health and Human Services (HHS), said the risk of a significant Ebola outbreak in the United States is “remote.”

“Based on the first U.S. cases, HHS has already made adjustments to minimize the spread of Ebola,” she said. “These include tightened guidance for the use of personal protective equipment, an expanded aggressive national education campaign for health-care workers, and screening and active monitoring of passengers entering the United States, now funneled through five airports.”

She said it was natural that procedures had changed after the disease appeared in the United States.

View Graphic What does an Ebola isolation ward look like?

But Deborah Burger, co-president of National Nurses United, told lawmakers that American health-care workers remained at risk. She said nurses had gotten inconsistent instructions, were often left to make decisions about proper precautions for themselves and at times had been forced to improvise their own protective gear.

She said only new, legally required guidelines would ensure medical facilities will provide workers the protection they need.

“The response to Ebola from U.S. hospitals and governmental agencies has been dangerously inconsistent and inadequate,” she said.

John Roth, the Department of Homeland Security’s inspector general, told lawmakers that the administration had mishandled a nearly $50 million program to prepare for pandemics.

The Department purchased coveralls and surgical masks, for example, that may have been unneeded, while other gear, such as respirators, had expired, Roth said. Officials are now working to address those problems, he said.

“I think it’s evident by the hearing today and hearings that will go on that you’re not bringing us a sense of security,” said Tim Walberg (R-Mich.).

Lawmakers also probed officials about plans for protecting troops sent to West Africa.

“The safety of our service members . . . is absolutely paramount, and while you can never mitigate risk to zero, I think we’ve taken all the steps to mitigate the risk,” said Michael Lumpkin, assistant secretary of defense for special operations and low-intensity conflict.

Officials acknowledged the U.S. government would currently only be able to bring less than 10 symptomatic soldiers home per week. The military is working to develop isolation pods that could move up to 15 sick patients by air at a time.

Defense officials explained some guidelines for keeping soldiers safe in West Africa. For example: asking soldiers to stand three feet from local nationals and washing their hands with chlorine. Soldiers’ temperatures will be taken twice a day.