NEW YORK, Nov 18 (Reuters) – Airport workers at seven of the busiest U.S. hubs plan to strike beginning Wednesday night over what they say are bad wages and threats against unionizing.

Some 2,000 plane cleaners, baggage handlers and other workers will strike at New York’s Kennedy and LaGuardia airports, as well as Newark Liberty, Chicago O’Hare, Boston, Philadelphia and Fort Lauderdale, the Service Employees International Union (SEIU) told Reuters.

The walkout, which has yet to be announced publicly, comes just before air travel picks up for the Thanksgiving holiday. It was not immediately clear if the action would cause flight delays because airlines often have backup plans to avert disruptions.

The strikers work for companies that U.S. airlines contract for some airport operations. That means pilots, flight attendants and in-house baggage handlers are not taking part in the action.

The SEIU, which seeks to unionize these workers, declined to name their employers in advance of the strike so the companies could not prevent it or threaten retaliation.

“We don’t receive enough money to pay the rent,” said Damaso Mejia, a worker involved with the SEIU who cleans and checks plane interiors for suspicious objects at New York Kennedy for $10.10 an hour.

He said he will start working a second job next month and will log 18-hour days to supplement his income.

The walkout has been in the works since the SEIU sponsored a convention in Washington a month ago for airport workers to discuss their concerns. The SEIU said some workers perceived threats against organizing.

U.S. Senator Chuck Schumer and several congressmen will attend a news conference in Washington on Thursday to garner support for $15 hourly wages, the union said. Rallies are to take place at other U.S. airports.

On Tuesday the SEIU endorsed Democratic presidential front-runner Hillary Clinton for the November 2016 election. Clinton said last month in a letter to the SEIU, seen by Reuters, that “airport jobs should be good jobs – and together, we can make sure they are.”

Plans by some New York airport workers to strike in July, supported by the SEIU, were called off after a last-minute agreement with their employer Command Security Corp.

(Reporting By Jeffrey Dastin; Editing by Sandra Maler)