Story highlights Philadelphia International Airport workers voted Tuesday to strike during the Democratic National Convention

Homeland Security Secretary Jeh Johnson will travel to Cleveland on Friday and Philadelphia the following week

(CNN) When Democrats arrive in Philadelphia later this month for their party's convention, they might be met by a picket line.

Workers at the Philadelphia International Airport voted Tuesday to go on strike during the Democratic National Convention, which is scheduled to be held July 25-28.

As many as 1,000 workers -- including baggage handlers and airplane cleaners -- could walk off the job and participate in the strike. Among other things, the workers are seeking improved benefits and schedules, as well as an ability to unionize.

Although the workers intend to strike during the convention, no precise dates have been set."

A representative for the Democratic National Convention Committee did not respond to a request for comment.

Read More