When UN envoy Nikki Haley talks, does President Trump listen?

A crucial test of her influence on him will come this week during Mr. Trump's maiden visit to the United Nations

On a Friday in August, the president of the United States casually said at a televised news briefing that his administration could not rule out a “military option” to respond to the crisis in Venezuela.

A look of bewilderment washed over the face of the woman standing next to him: Nikki R. Haley, President Trump’s ambassador to the United Nations. She knit her brows, looked at him briefly, looked down at her hands.

Twitter reacted immediately. “Nikki Haley’s face,” wrote one.

“We are all Nikki Haley right now,” wrote another.

“Hey, she accepted the job,” wrote a third.

That moment embodied the challenge that confronts