Delta and Northwest are betting that cost cuts and the benefits of a bigger route network will outweigh the potential operating chaos and labor unrest that can result from airline mergers.

The long-expected Northwest-Delta deal could be quickly followed by another merger, airline executives and industry analysts said.

The leading candidates are United and Continental Airlines, which have explored the idea. The airlines may now try to get the deal wrapped up within the next 30 days, a person with direct knowledge of the negotiations said Monday night. He spoke on condition of anonymity because the talks are private.

One reason for the urgency is that airlines want to get their deals approved by the Justice Department under the Bush administration, rather than risk seeing them stall until a new president takes office.

United’s chief executive, Glenn F. Tilton, has been eager for a merger, but Continental had resisted, saying it wanted to wait to see if the combination between Delta and Northwest came about. The chief executive of Continental, Lawrence W. Kellner, called it “good news” last month when it appeared that the Delta-Northwest talks had cooled. But Mr. Kellner could end up running the combined Continental-United, should an agreement take place, this person said.

Such deals would put pressure on others to explore combinations or consider restructuring, analysts said. American Airlines, which avoided Chapter 11 bankruptcy earlier in the decade, may be forced to explore that possibility so that it can rid itself of aging aircraft leases, and reduce its labor costs. Or, American could seek a deal with a smaller airline such as JetBlue Airways, in order to gain access to JetBlue’s younger fleet.

Meanwhile, Southwest Airlines, which has been the healthiest of the American carriers, may be forced to explore a deal with a low-fare carrier like AirTran, so that it can maintain its hold on the market for bargain minded travelers.