WASHINGTON — Anticipating another holiday travel crunch, President Bush said on Tuesday that his administration was taking steps to prevent frustrating flight delays during the busy Thanksgiving and Christmas holiday seasons.

To reduce air congestion, Bush said airspace typically dedicated to the military will be temporarily opened to commercial airliners. Last year, the Pentagon freed up two East Coast corridors during Thanksgiving; Bush said that was being expanded this year to include the Mideast, the Southwest and the West Coast, including the skies around Los Angeles and Phoenix.

The military uses the space for exercises, but often makes some available to commercial planes on an ad hoc basis. This move would allow airlines to count on the extra room in the skies, which will be especially helpful if bad weather further snarls air traffic.

"A lot of our citizens are nervous about travel," Bush said in remarks before hundreds of employees at the Department of Transportation.

"They are saying `Will traveling home for the holidays be a wonderful life or will it be the nightmare before Christmas?"' Bush said, referring to the films, "It's a Wonderful Life" and "The Nightmare before Christmas."

With planes expected to be about as crowded this year as last, the president announced other steps — most already in the works or tried before — aimed at easing congestion.

He said his administration was working with the Federal Aviation Administration, the Transportation Security Administration and the airlines to make more staff available to speed check-ins and boarding.

The president also said new regulations will be in place in time for the Christmas travel crush that raise the amount airlines must pay to travelers for lost bags and if they fail to notify passengers about hidden fees. Another recently implemented rule requires airlines to pay higher bump fees when travelers who buy tickets wind up without a seat.

In addition, he announced that he had signed an executive order to make modernizing the nation's aviation infrastructure a top priority for all federal agencies.

Bush's decision to open the military air corridors was applauded by Delta Air Lines Inc. "We've long been a proponent of cooperative efforts to allow airlines to use military air routes to better manage air traffic flow and alleviate congestion," said Delta spokeswoman Betsy Talton.

Others who closely monitor air traffic said the modest moves were welcome, but don't address the heart of the problem.

"It had marginal impact" last year, said David A. Castelveter, vice president for communications at the Air Transport Association, a trade group representing major airlines. "The main reason for the good performance we saw over both holidays last year was good weather."

The union representing air traffic controllers also said last year's efforts made little difference, and that this year's steps are unlikely to provide any significant relief either.

"It is all for show and, frankly, this show is getting quite tiresome to the American traveling public that has gotten fed up with mounting delays and FAA mismanagement that has degraded the system during the current administration," National Air Traffic Controllers Association spokesman Doug Church said.

Approximately 24 million passengers are expected to fly over the 12 days considered to cover the Thanksgiving holiday this year, Castelveter said. That's about 10 percent fewer than last year, but airlines also have removed about 10 percent of their capacity from the system, meaning planes will be just as crowded. Castelveter said airplanes will be about 90 percent full at peak travel times and will be 100 percent full in key markets.

Bush noted his administration's work to fix a main source of flight delays: problems at the three major New York City-area airports, John F. Kennedy, LaGuardia and Newark-Liberty. The government says two out of three flights delayed 15 minutes or more were due to cascading backups beginning at one of those three airports.

So the administration is conducting an experiment to auction off takeoff and landing times at the three. An auction, they say, will use market forces of supply and demand to make airports more efficient, and they are racing to get the auction plan in place before they leave office in three months, with auction winners to be announced in early January. At the same time, airlines and airports are sprinting to court to stop them.

Bush also highlighted the Transportation Department's plan to spend $89 million on taxiway improvements at Kennedy, and the capping of flights permitted to come into or out of the three New York-area airports.

And he said that three new runways were opening Thursday at big, busy airports: Washington-Dulles, Chicago-O'Hare and Seattle. That brings to 14 the number of new runways over his administration, Bush said.