The Republican National Committee said in a statement Monday that Wicker, 56, was "a shining example of the kind of dedication we all hope for in our public servants."
Wicker has represented Mississippi's 1st Congressional District since 1994 and was a two-term state senator.
Barbour didn't announce a date for an election to replace Wicker in the U.S. House of Representatives.
Lott, R-Miss., retired Dec. 18 after first being election to the Senate in 1988.
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