west - 5-18 - morigi- Darrell M. West is Vice President and Director of Governance Studies at the Brookings Institution.  He is the author of the forthcoming Brookings Institution Press book, Brain Gain:  Rethinking U.S. Immigration Policy. The opinions expressed are his own -

Michelle Obama is a hit at home and abroad but she will come under particular scrutiny this week as she embarks on her first solo trip outside the U.S., visiting Mexico. How she performs on this diplomatic mission will be closely watched because she is not just the president’s wife, she is the most prominent ambassador for her husband’s foreign policies.

Such trips are not a small undertaking, and they can carry more weight than might be expected.

When the First Lady travels abroad, foreigners take cues about policy substance and tonality from her.  They understand she is the last person the president sees at the end of many days.  Advice that she offers has a meaningful impact on substantive policy.

That Mrs. Obama is traveling to Mexico on her first solo outing is also significant. The country is vital to long-term American interests.  We share two thousand miles of border with our southern neighbor, and our economies are intimately intertwined.  Mexico is America’s second largest trading partner, and there are more than one million daily border crossings between the two nations.  Many of our undocumented immigrants come from Mexico.