WASHINGTON (Reuters) -The head of a U.S. airline trade group urged an end to the 15-day government shutdown, citing concerns about rising pressure faced by air traffic controllers working without pay.

"It's got to stop like now, because every day that goes by, the pressures get higher, the risks get higher," Chris Sununu, CEO of Airlines for America, a major trade group representing carriers American Airlines ( AAL ), Delta Air Lines ( DAL ) and United Airlines, said in an interview. "You're getting closer and closer to those air traffic controllers just feeling financial pressures."

Aviation groups are growing more worried about the potential impact of a longer government shutdown after mounting sick calls by controllers have resulted in thousands of delays since the shutdown began. The Air Line Pilots Association and National Air Traffic Controllers Association have both called for a quick end to the shutdown.

More than 13,000 air traffic controllers and 50,000 Transportation Security Administration officers received a partial paycheck in recent days and will not get paid later this month if the standoff is not resolved.

Sununu, a former New Hampshire governor, said things could worsen.

"I think it'll really hit ahead, probably about a week and a half from now, when that first zero paycheck comes," Sununu said. "Most people can survive a couple but after three weeks, that just puts real strain on the system."

Sununu wants a continuing resolution to reopen the government but acknowledged the need for a healthcare debate sought by Democrats.

"I don't care about the politics. I just care about the easiest way to make sure the system has resilience," Sununu said. "If the system comes to a screeching halt for whatever reason, that's felt on a worldwide scale. ... Hopefully they'll realize it before we get there."

In 2019, during a 35-day shutdown, the number of absences by controllers and TSA officers rose as workers missed paychecks, extending checkpoint wait times at some airports. The Federal Aviation Administration was forced to slow air traffic in New York, which put pressure on lawmakers to quickly end the standoff.