NEW YORK — Airport security workers at John F. Kennedy International Airport, whose duties include guarding doorways and performing secondary screenings of some passengers, voted Thursday to go on strike at the height of the holiday travel season next week to press demands for higher pay, better conditions and the right to unionize.

Employees of two companies, Air Serv and Global Elite Group, are involved in the strike threat, and while their numbers aren’t large — about 300 workers in all would be involved — they say their jobs are crucial to passenger safety.

“Their safety is in our hands, and right now it is at risk,” one worker, Prince Jackson, said of travelers as about 100 supporters of the employees held a loud protest outside Terminal 3 at the airport. “They will be completely unsafe” if the strike goes ahead Dec. 20, as Air Serv workers threatened in a vote Thursday. Global Elite Group employees were due to vote Friday and expected to also approve a strike.

The strike threat comes on the heels of a one-day walkout last week by New York fast-food workers with many similar gripes. One of the main issues surrounds the non-union workers’ demands to join unions, which would lift their wages.

Jackson said he was hired by Atlanta-based Air Serv three years ago at $8 an hour. “I still make $8 an hour,” said Jackson, whose duties include making sure passengers don’t come back after passing through exits, and ensuring that employee entrances are not used by others.

Jackson said training was shoddy for new employees, and he described one new worker being posted to guard a doorway with no more than a paragraph of written instructions on how to do the job. As a result, she inadvertently let a passenger reenter through an exit. “It could’ve been anybody coming through that door,” Jackson said.

Rahman Baksh, another Air Serv employee, said he was on duty recently in Terminal 2 when someone spotted a piece of unattended luggage. He was unable to alert security using his Air Serv two-way radio because the batteries were dead, which Baksh said was common. “I had to leave the unattended bag unattended,” said Baksh, who went to find a phone to call someone to check the bag.

Airport security is a hot-button issue in New York, where more than a dozen terrorist plots have been foiled since the Sept. 11, 2001, attacks.

Air Serv issued a statement saying it only became aware of the complaints this week. “We are now in the process of reviewing them,” it said.

The would-be strikers have the support of unions, clergy and politicians, who say the recession has left service jobs as the only option for many, and that not giving workers any hope of pay hikes or improved conditions amounts to workplace abuse.

“JFK is New York City’s gateway to the world,” said the city’s public advocate, Bill de Blasio, who attended the airport protest. “This needs to be the safest facility on earth, but it’s not.”

tina.susman@latimes.com