ATLANTA — As it continues grappling with challenges to its core brands, Coca-Cola is rethinking the way it selects the PR firms with which it works, the Holmes Reports has learned.

According to individuals familiar with the activities, the iconic beverage company in late 2017 invited a range of firms to apply to be on the company’s approved vendor list. Agencies that make the cut are able to pitch work as it becomes available, added sources.

One source called the move a “macro shift” for Coke and its agency selection process.

The world’s largest beverage company, Coca-Cola uses a multitude of PR and creative agencies around the world, often tapping them for assignments centered around particular products (the giant has more than 500 fizzy and still brands) or initiatives, sources said.

Over the years, a range of agencies —UM, Wieden+Kennedy, Ogilvy and Weber Shandwick (whose had a 15-year relationship with Coke until 2007) among them — have worked in various ways with Coca-Cola, some of whose marketing and advertising campaigns rank among the industry’s most memorable.

The change in building relationships with agencies comes as the company tries to recover from recent sales slumps, fueled by factors from the growing war on sugar to being behind in digital marketing and tools.

One of Coca-Cola’s core components of turning things around is promoting its sugar-free brands as healthy alternatives to the soda on which it was founded. The company is, for instance, is currently in midst of rolling out three new flavors of Dasani Sparkling, the carbonated water brand Coca-Cola launched with four flavors in 2014.

The change in agency dealings also comes with a new marketing exec running the department — Bea Perez, who stepped into the role of The Coca-Cola Company senior VP and chief public affairs, communications and sustainability officer last May. Formerly VP and chief sustainability officer, Perez expanded her duties in May when Clyde Tuggle, the previous chief public affairs and communications officer, retired after 28 years with the company.