WASHINGTON, D.C.: Facing the prospect of Presidential intervention in their labor dispute, the American Airlines pilots union softened its stand and offered to accept lower wages for flying smaller "regional jets." Even so, airline management rejected the offer, encouraged by reports that President Clinton is considering forcing pilots to stay on the job. Worried about the economic impact of losing 20 percent of the nation's airline capacity overnight, Clinton has asked for a detailed estimate of a strike's economic impact, but is so far dancing around whether he will step in before the midnight Friday deadline. A shutdown at American could ruin the season for the travel industry in the Caribbean and Colorado, where the airline provides about half the service. Neither side is optimistic that a settlement will be reached. Pilots have been advising passengers to rebook their weekend flights with other airlines, while American has already begun canceling both domestic and overseas flights. The pilots say they would accept lower wages for flying the 40 to 75-passenger regional jets, a growing part of the market, as long as their union, the Allied Pilots Association, is allowed to represent the pilots. APA pilots' salaries average $120,000, but the industry wage for pilots of regional jets is about $35,000. American quickly slammed the door on that proposal, saying it wants to use pilots from its commuter service, American Eagle. Said one spokesman: "In reality, those jets are going to be operated as American Eagle or they are not going to be operated. There are costs involved beyond pilot costs." Those costs could be considerable, since if American Airlines pilots are placed on those flights, every other employee working on the flights, from baggage handlers to mechanics, will have to be paid the major-carrier scale as well. Still, the proposal, floated early Thursday morning, is a sign that progress has been made during this week's closed-door negotiations. The pilots' new flexibility may be a signal that American is willing to approve their wage demands -- an 11-percent increase over four years -- or offer the stock options the pilots desire.