Mr. Stewart, 45, will leave by June 30, and the Kmart marketing team will report to Maureen McGuire, chief marketing officer of the chain's parent, Sears Holdings, until the company completes a search for a replacement, a spokesman said.
Blue light shines anew
In a memo to staff reporting the move last week, Ms. McGuire praised Mr. Stewart's work, which included the return of Mr. Blue Light to Kmart advertising earlier this year. The Chicago Tribune first reported Mr. Stewart's decision yesterday.
"We've had a great run and come a long way toward our goal of getting America to take another look at what we have to offer," Mr. Stewart told Advertising Age.
But he said he felt personally compelled to go in a different direction because of a historic vote approaching in California. "It was something that personally was so important to me that I felt I needed to do everything possible," he said.
Mr. Stewart, who's on the board of directors of the Gay and Lesbian Alliance Against Defamation, will become a full-time volunteer for Equality for All, which is leading the campaign against a ballot initiative to overturn a California Supreme Court decision earlier this year and ban gay marriage.
Both Kmart and its corporate sibling Sears have struggled for years, before and after financier Edward Lampert, now chairman of Sears Holdings, pieced together the two retailers into a single company in a turnaround bid.
Finding its way in 'tough market'
In an Advertising Age profile of Ms. McGuire last month, Sears Holdings interim CEO Bruce Johnson said, "It's a tough market out there now, but we like the direction that we're going and the emphasis on some of the new and emerging forms of marketing media."
Interpublic Group of Cos.' DraftFCB, Chicago, handles creative for Kmart.
Recent ads showed women chosen for casting calls to become Kmart's "fashion ambassador" guessing if the clothes they'd been trying on came from Barneys New York or H&M rather than the discount retailer.