Washington (CNN) Mississippi Gov. Phil Bryant plans to appoint state agriculture commissioner Cindy Hyde-Smith to replace retiring Sen. Thad Cochran, three Republican sources said.

Hyde-Smith, who would become Mississippi's first-ever female senator, would hold the job until a November special election in which voters will select a candidate to fill the remaining two years of Cochran's term.

If Hyde-Smith runs to keep the job, it would set up a three-way showdown with Republican state Sen. Chris McDaniel -- who has already announced his candidacy -- and Democratic former Rep. Mike Espy.

The special election, held on the same day as this year's midterm elections, comes with a unique twist: There's no primary, and candidates will run without party labels. If no one breaks 50%, the top two finishers, regardless of party, would advance to a runoff.

Hyde-Smith, a 58-year-old beef cattle farmer, served as a Democrat in Mississippi's state senate before switching parties.

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