WASHINGTON — As summer winds down, Congress is lining up its autumn hearings. But airline mergers, the subject of four hearings this spring, are not among the hot-button issues scheduled for attention.

With no more congressional reviews planned, conventional wisdom now holds that the proposed merger of Delta Air Lines and Northwest Airlines will be completed this year without any major new political objections.

Further hearings are unnecessary because "we believe that Congress saw that antitrust (violations) would not be a significant concern with this deal," Delta spokeswoman Chris Kelly said.

Politics is not supposed to play a role as attorneys at the Justice Department review a merger for possible antitrust violations. That department alone has the power to block a deal if it threatens competition in an industry.

But elected lawmakers can play an indirect role in the review process by whipping up popular sentiment to pressure the Justice Department. The House and Senate hearings held in April and May, shortly after the deal was announced, failed to create a firestorm of protests, leaving the Delta-Northwest merger seemingly cleared for takeoff in coming months.

"We are pleased with the progress that has been made and believe we are on track for completion by the end of the year," Kelly said.

Andrew B. Steinberg, an aviation attorney and former chief counsel for the Federal Aviation Administration, agreed. "I have not heard there are any problems," he said.

Justice spokeswoman Gina Talamona would say only that the review is "ongoing."

But even though the merger appears on track, some opponents say they will continue to object. Joseph Tiberi, spokesman for the International Association of Machinists and Aerospace Workers, said he is in no mood for surrender.

"We've been opposed to this from Day One, and our opposition will continue," said Tiberi, whose union represents Northwest's customer-service and reservation agents, clerical workers and equipment service employees. "We will continue meeting with members of Congress and take all steps possible to protect workers, because Delta and Northwest management clearly are not."

He said this year's hearings did nothing to persuade the IAM that the merger would be good for workers. "If anything, we are less comfortable with it," he said, because during their testimony, the airlines' executives pulled back from their initial pledge not to fire front-line workers.

Instead of reaffirming a no-furlough commitment, they told Congress "high fuel prices may make that impossible," he said. "We have seen Delta and Northwest change their stories."

Delta's Kelly said the airlines have consistently said there would be no furloughs as a result of the merger. Whether employees would be cut because of high fuel prices would be a separate issue, she said.

Frank Werner, a Fordham University professor who has been studying the proposed merger, said politics is playing a role in the merger's timing. "They are hustling to get this done before the Bush administration leaves," he said.

The airlines "chose to announce this merger in 2008 in part because of their belief that the Bush administration has been very pro-management," Werner said. "Historically, Democrats have been more critical of mergers," and even a White House under Republican John McCain may be more skeptical of the benefits of a reduced number of major carriers, he said.

Werner said that given how fares have risen and routes reduced this year, "I'm a little bit surprised there hasn't been more outcry from the public," he said. But the answer may be that fuel prices have risen so high consumers actually have sympathy for the carriers, rather than resentment, he said.

"Every individual is hurting too," he said. "So maybe the merger is an easier sell for the airlines."