CHICAGO — McDonald’s franchisees want the company to focus on making an excellent chicken sandwich as they face a rising threat from fast-growing Chick-fil-A.

The National Owners Association, an independent group representing McDonald’s U.S. franchisees, sent a letter to its members Wednesday warning of Chick-fil-A’s expansion and said Chicago-based McDonald’s does not have a premium grilled or crispy sandwich that can compete.

“A favorite, that our customers want, is a chicken sandwich,” read the emailed letter from the group’s board. “Unfortunately, they have to go to Chick Fil A for it. Chick Fil A’s results demonstrate the power of chicken.”

Atlanta-based Chick-fil-A grew sales 16.7 percent last year, to nearly $10.5 billion, vaulting past its competition to become the nation’s third-largest restaurant chain after Starbucks and No. 1 McDonald’s, according to industry publication Nation’s Restaurant News.

Chick-fil-A, which made those sales despite being closed on Sundays because of the owners’ Christian beliefs, also has ranked first in the American Customer Satisfaction Index for four years in a row.

While McDonald’s sells Chicken McNuggets and a McChicken sandwich, and its recent introduction of items from its international menus brought Canada’s Tomato Mozzarella Chicken Sandwich to U.S. restaurants, it falls short of having a category-leading chicken sandwich, said the letter from the franchisee association. The group formed last year in response to franchisee frustration with mandatory store remodels that were squeezing profits, prompting the company to push the remodel deadline back by two years. More than 90 percent of McDonald’s 14,000 U.S. restaurants are owned by franchisees.

The company’s Southern Style Chicken sandwich, which was discontinued from the national menu years ago, was “very close to category leading,” the letter said, but would be improved by buttering the bun and serving it in a foil bag. That’s how Chick-fil-A serves its sandwiches.

“JFK called for a man on the moon, our call should be a category leading chicken sandwich,” the letter said.

A McDonald’s spokeswoman did not immediately respond to a request for comment.

McDonald’s, which reported more than $21 billion in global sales last year, has been adjusting its menu and pricing as it grapples with declining foot traffic. The fast food chain has been focused on improving its Quarter Pounder, and says the introduction of fresh beef resulted in 40 million more Quarter Pounders sold in the first quarter of this year compared with a year before. Sales spiked 50 percent in the first month of the promotion in May 2018.