WASHINGTON — Facing a growing backlash over extremely long airport security lines, Homeland Security Secretary Jeh Johnson on Friday asked fliers “to be patient” as the government takes steps to get them onto planes more quickly.

Travelers have endured lengthy lines, some snaking up and down escalators, or through food courts, and into terminal lobbies. At some airports, lines have topped 90 minutes. Airlines have reported holding planes at gates to wait.

Johnson said the government has a plan to deal with the lines but won’t neglect its duty to stop terrorists. “Our job is to keep the American people safe,” Johnson told reporters. “We’re not going to compromise aviation security in the face of this.”

The Transportation Security Administration has fewer screeners and has tightened security procedures. Meanwhile, more people are flying. Airlines and the TSA have been warning customers to arrive at the airport two hours in advance, but with summer travel season approaching even that might not be enough.

In the past three years, the TSA and Congress cut the number of front-line screeners by 4,622 — or about 10 percent — on expectations that an expedited screening program called PreCheck would speed up the lines.

However, not enough people enrolled for TSA to realize the efficiencies. Congress did agree to shift $34 million in TSA funding forward, allowing the agency to pay overtime to its existing staff and hire more screeners.