Story highlights "We don't give into our fears. We don't build up walls to keep people out," Obama said in New York City

It was an unmistakable reference to Trump's signature policy proposal

New York (CNN) Michelle Obama used her final commencement address as first lady Friday to deliver some thinly veiled shots at the man who wants to succeed her husband: Donald Trump.

"We don't give into our fears. We don't build up walls to keep people out because we know that our greatness has always depended on contributions from people who were born elsewhere," Obama told the graduating class at City College in New York City.

It was an unmistakable reference to Trump's signature policy proposal -- to build a wall on the border between the United States and Mexico -- as well as his campaign's indelible slogan, "Make America Great Again."

The commencement address capped what has been a week-long tag-team effort between the Obamas and Hillary Clinton, likely a preview of what the Democrats have planned for their general election campaign against Trump.

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