A federal judge rejected a request by former Northwest Airlines Corp flight attendants to raise their compensation to that of Delta Air Lines Inc colleagues who worked at that carrier before the companies' merger.

While rejecting Delta's bid to dismiss the case, U.S. District Judge Patrick Schlitz in Minneapolis said the former Northwest flight attendants were unlikely to ultimately prevail on their claims for equal pay and benefits. He denied their request for a temporary order to align their compensation.

Robert Clayman, a lawyer for the former Northwest flight attendants, did not immediately return a call seeking comment. Delta spokeswoman Gina Laughlin said the carrier is pleased the court did not issue a preliminary injunction.

The lawsuit filed on March 2 accused Delta of withholding profit-sharing checks from more than 7,500 former Northwest flight attendants, giving them less than half the amount paid to their pre-merger Delta colleagues.

It followed a February 14 announcement by Delta Chief Executive Richard Anderson, who once held the same job at Northwest, of a $313 million profit-sharing award.

Before the carriers merged in October 2008, Northwest flight attendants were unionized, while Delta flight attendants were not and were paid more.

The plaintiffs, five Delta flight attendants who once worked at Northwest, said Delta paid them and their Northwest colleagues less because of their past union membership.

In his decision, Schlitz said the balance of harms weighed in favor of ruling now for Delta, even if the former Northwest flight attendants were ultimately to win.

If the court were to order Delta to grant pay raises and a larger profit-sharing distribution to plaintiffs, and Delta were later to prevail in this litigation, Delta would be unlikely to be able to recoup its losses, he wrote.

Moreover, the judge added, any attempt by Delta to recoup its losses would likely have a more destabilizing effect than would delaying any monetary recovery to which plaintiffs eventually prove themselves entitled.

Schlitz added that the former Northwest flight attendants' broader interest in protecting their right to unionize is being addressed by a federal mediation board.

The combined airline is based in Atlanta and is the second-largest U.S. carrier, after United Continental Holdings Inc . Northwest had been based in Minneapolis.

In late afternoon trading, Delta shares were down 41 cents, or 5.1 percent, to $7.59.

The case is McMahon et al v. Delta Air Lines Inc, U.S. District Court, District of Minnesota, No. 11-00521.

(Reporting by Jonathan Stempel in New York; editing by Carol Bishopric)