SEATTLE — As cars and pedestrians passed by during the evening rush on Thursday, Paula Harper-Christensen, a retired teacher, smiled and waved her sign with an upside-down Starbucks mermaid. “Don’t spill our chance,” the text said under the logo. Susan Glicksberg’s protest placard was more blunt: “Do Not Run!”

Howard Schultz, the former chief executive of Starbucks, has returned to his hometown, Seattle, and it has not been a uniformly warm welcome.

Mr. Schultz, 65, has come under fierce criticism from many fellow Democrats for being a possible 2020 spoiler after he disclosed his interest in running as an independent candidate for president. He says he will weigh whether to run over the few next months as he undertakes a national book tour describing his vision for fixing America’s ills.

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Thursday night was his first major appearance in Seattle since his political announcement. Roughly 40 protesters gathered to greet him before his planned event to promote the book and his possible candidacy. Some, like Mary Hanke, were overtly hostile to Mr. Schultz and his record as a businessman.