Two unions are partnering to make another run at unionizing flight attendants at Delta Air Lines, after several failed attempts by one union.

The Association of Flight Attendants and the Transport Workers Union say they are in the early stages of planning a campaign to seek a representation vote among Delta’s more than 19,000 attendants.

The AFA has lost three elections at Delta in the last 10 years, with the most recent following Delta’s 2008 acquisition of Northwest Airlines, whose flight attendants the union had represented.

After the AFA lost that 2010 election, some union advocates raised the possibility of trying to organize under a different union.

“There was a lot of interest” in TWU from Delta flight attendants over the years, Transport Workers Union spokesman Jamie Horwitz said.

The two unions say they will provide assistance from their legal teams and advise the Delta flight attendants group on organizing as the Association of Delta Flight Attendants.

Delta is mostly non-union, with pilots the only major employee group represented. Many airlines are more heavily unionized.

In a written statement, Delta said flight attendants “have rejected AFA representation multiple times over many years, so we’re not surprised AFA would try to put on a different face this time.”

To get a vote, organizers must collect signed cards from at least 50 percent of the eligible work group, a process that can take months or years.

The AFA is the world’s largest flight attendant union, while the TWU represents different airline employee groups, including flight attendants at Southwest.