There were new rumblings Thursday that a merger between Atlanta-based Delta Air Lines and Northwest could be close, but it won't be the pretty marriage some executives first envisioned.

One published report indicated Delta and its pilots union have "agreed in principle on a contract" that could clear the way for the carrier to combine with Eagan, Minn.-based Northwest to create a mega-airline.

However, people familiar with the negotiations told The Atlanta Journal-Constitution the report may be premature.

"A tentative agreement is a long way from being approved," said one senior Delta pilot, who asked not to be named. "It's not like something that will change our lives tomorrow."

Bloomberg News, citing unnamed sources, on Thursday reported Delta management had reached an agreement in principle with the Delta pilots union that would include higher pay and an equity stake in the combined carrier.

Any pact would need to be approved by the leaders of the Delta pilots union, a unit of the Air Line Pilots Association, before the carriers could finalize their deal. The Delta union's 6,000 members also may vote later on whether to ratify a new labor contract tied to the merger.

An agreement struck solely between Delta and its pilots on what their contract would look like after a merger would not have the far-reaching sweep management had hoped for. Executives at Delta and Northwest wanted both pilot groups to agree to how they would work in a combined company. The two pilots unions met for weeks but got stuck on a key issue -- seniority -- and ultimately walked away from the negotiating table.

Seniority is a key issue for pilots as it determines their pay, what planes they fly and which routes they get. Delta's pilots generally have lower seniority than Northwest's pilots because hundreds of the Atlanta carrier's most senior pilots retired before the company filed bankruptcy in 2005.

When the Delta-Northwest pilot negotiations broke off, so did merger talks. But about two weeks ago the companies resumed discussing a deal, even without full pilot buy-in.

It could be a risky strategy. US Airways and AmericaWest did not get pre-merger agreements from their pilots before they combined in 2005. Today, those pilots still are working under separate seniority lists and contracts, weighing down operational integration. Pilot opposition also could hurt the companies' chances of getting government approval to combine.

Any merger would have to be approved by federal regulators and final consolidation of airline fleets, routes, computer systems and pilot contracts could take years.

The Delta-Northwest combination might initially be a "merger lite," according to some analysts. Headquarters would remain in Atlanta, but the two carriers could initially operate under a holding company that would produce some cost savings but avoid thorny issues like seniority standing for the two carriers' 11,000 pilots.

Northwest pilots already were balking Thursday.

A spokesman for Northwest's pilots union, which has about 5,000 members, indicated that the merger could run into serious obstacles.

"We are unaware of any developments at this time and will hold specific comments until details are confirmed. We would suggest, however, any negotiations that do not involve all parties are rarely successful," said Northwest union spokesman Greg Rizzuto.

On its Web site, the Northwest pilots union told members that its leadership committee has scheduled a special meeting Sunday in Bloomington, Minn., to "update the [union leaders] on industry consolidation and negotiations."

A Delta spokesman declined to comment on the latest development. Union officials at Delta's pilot union could not be reached for comment.

Delta-Northwest merger agreement could be announced as early as next week. A Delta-Northwest combination could kick off a wave of mergers among financially battered carriers struggling with soaring fuel costs, a weakening economy and withered stock prices. Delta, in a company filing, said Thursday it expects to report a net loss in the first quarter. Its stock closed at $9.75, up 9.4 percent. Northwest closed at $10.87, up 13 percent.