ATLANTA — Some Delta Air Lines Inc. flight attendants are seeking to unionize as the nation's No. 3 carrier considers combining with Northwest Airlines or United Airlines.

A past effort by Atlanta-based Delta's flight attendants to unionize failed. Delta's pilots are currently the only major work group at the company to be part of a union.

The latest efforts by the flight attendants come as consolidation talks involving Delta intensify. Delta also has been talking to UAL Corp.'s United Airlines, officials familiar with the discussions have said.

According to the Association of Flight Attendants-CWA, Delta flight attendants filed cards on Thursday seeking a union representation election.

At least 35 percent of Delta's 12,000 active flight attendants must sign cards seeking union representation for the National Mediation Board to call an election, Delta spokeswoman Gina Laughlin said.

If the number of cards is verified, the NMB would call an election involving all Delta flight attendants. In an election, more than 50 percent of all Delta flight attendants must vote for union representation for the proposal to pass, Laughlin said. It could be several months before an election is called.

A similar effort in late 2001 was rejected in election results announced on Feb. 1, 2002.

More than 55,000 flight attendants at 20 airlines are members of the AFA-CWA. The AFA is part of the 700,000-member Communications Workers of America.

An AFA-CWA spokeswoman, Corey Caldwell, said the process involving Delta's flight attendants is currently in the NMB's hands.

AFA-CWA represents Northwest's roughly 8,000 flight attendants.