SIOUX CITY, Iowa — South Carolina Gov. Nikki Haley plans to endorse Mitt Romney's presidential bid.

A Republican with knowledge of the endorsement disclosed the plan ahead of the official announcement on condition of anonymity.

Haley is a rising star within the GOP and her endorsement in the first-in-the South primary state has been sought by many other presidential contenders.

Romney plans to fly to South Carolina on Friday afternoon.

Politico first reported the Haley endorsement.