Obama shakes hands with Castro during a memorial service for former South African President Nelson Mandela in Soweto, South Africa, on Dec. 10, 2013. Former Cuban leader Fidel Castro says his brother introduced himself to Obama in English, telling him, "Mr. President, I'm Castro," as the two leaders shook hands. AP hide caption

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Republican Senator-elect Thom Tillis of North Carolina says he expects his party to challenge the president immediately on immigration, and that he hopes President Obama's Defense and Justice nominees will be acceptable to both parties. Davis Turner/Getty Images hide caption

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Sarah Obama, left, and her translator, Mama Sarah Obama Foundation Executive Director Debra Akello, spoke at the United Nations on Wednesday. Bebeto Matthews/AP hide caption

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