The head of the transportation security administration warned travelers that a boycott of full-body scans will only cause delays at airports.
TSA Administrator John Pistole said that with Wednesday being one of the busiest flying days of the year, a boycott would only "tie up people who want to go home and see their loved ones."
"We all wish we lived in a world where security procedures at airports weren't necessary," he said. "But that just isn't the case."
Pistole's caution comes as an Internet campaign is urging travelers to boycott airport body scans on Wednesday in what is being dubbed National Opt-Out Day.
"Just one or two recalcitrant passengers at an airport is all it takes to cause huge delays," said Paul Ruden, a spokesman for the American Society of Travel Agents. The group has warned its more than 8,000 members about delays.
So far, there has been little if any indication that such a revolt would take place, with few travelers declining the X-ray scan.
"Whatever keeps the country safe, I just don't have a problem with," Leah Martin, 50, of Houston, said as she waited to go through security at the Atlanta airport.
In the meantime, the TSA has continued to defend its new security procedures, citing U.S. intelligence reports of terrorists possibly using prosthetics or other medical devices to hide explosives.