The Service Employees International Union has postponed a decision on an endorsement until next month, a setback for Democratic presidential candidate John Edwards.

The SEIU's executive board has decided to wait until October before deciding which one of the three leading Democratic candidates — Hillary Rodham Clinton, Barack Obama or Edwards — to endorse, a spokeswoman said Tuesday.

"The executive board has decided to go back to the local members and ask their opinions before making a decision," spokeswoman Stephanie Mueller said.

This weekend marks the end of the third quarter fundraising period and will provide strong signals on the viability of the candidates. Edwards, a favorite of labor who has picked up several key endorsements, lags his top two rivals in fundraising and trails them in national polls.

During the first six months of the year, Obama led the Democratic field in money, raising $58.5 million. Clinton raised $52.5 million and Edwards raised $23 million. Clinton, however, had the most cash on hand at the end of June, with $45.2 million in the bank.

Clinton, the party's front-runner, also holds the edge in labor endorsements.

The 1.8-million member union winnowed the Democratic field to Clinton, Obama and Edwards after the three were the clear favorites at an SEIU forum in Washington last week. SEIU leaders asked for and met with the three candidates' campaigns in Chicago on Monday. Clinton, Edwards and Obama are scheduled to speak on Tuesday to the Change To Win labor conference.

Anna Burger, SEIU's secretary-treasurer, said many union officials had to leave after hearing the three presentations Monday, so they decided to postpone any action until their October meeting. She said the union didn't endorse until November 2003 and rejected suggestions that the delays could be hurting their eventual endorsee.

"This is earlier than we ever considered endorsing before, so it depends on your perspective," she said.

Officials with Change to Win's leadership told reporters Tuesday morning that they are struggling with whether to make an endorsement with so many candidates they support competing for the nomination.

"These are tough determinations," said Bruce Raynor, UNITE HERE's general president.

SEIU is one of the seven unions, including hotel workers, janitors, Teamsters and truck drivers, that broke away from the AFL-CIO to form the rival labor federation.

The SEIU endorsement is one of the most important labor endorsements available, with the organization donating more than $25 million to mostly Democratic candidates since 1989, according to the Center for Responsive Politics.