Baggage handlers, wheelchair attendants, airplane cleaners, and other workers at Philadelphia International Airport voted overwhelmingly Tuesday to walk off their jobs in protest during the Democratic National Convention this month, according to a union that wants to organize them.

The workers are seeking better scheduling, clarity on sick pay, a more predictable disciplinary system, and to be able to unionize.

The vote, which took place at the airport, was 461-5 in favor of striking out of 500 on shift Tuesday participating. The workers, who number about 1,000, work for subcontractors hired by various airlines.

Gabe Morgan, area vice president for SEIU 32BJ, which has been trying to unionize airport workers, said years of worker protests had already led to wage increases to $12 an hour.

The Philadelphia convention host committee declined to comment.

Morgan said no date for a strike had been set. The convention runs from July 25 to 28.

"The purpose of the DNC is to lift workers out of poverty," Morgan said. "What these workers are fighting for is what the DNC and the convention is supposed to be about."

Morgan said other area unions have fair contracts and thus would not have strikes during the convention, but that's not the case for the airport workers. He said that workers pushing for unions have been fired from their jobs.