Along with his takeout from the vegan chain Native Foods Café, Democratic Rep. Jared Polis of Colorado received this note: “The constituency has spoken. Use your power wisely. Feel the Bern.”

Mr. Polis, a superdelegate who has endorsed Democratic presidential candidate Hillary Clinton, acknowledged the pressure on him to change his position in a state where Sen. Bernie Sanders of Vermont handily won the Democratic caucuses. “Even my food takeout is lobbying me for #FeelTheBern,” Mr. Polis tweeted late last month.

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