New Delhi, July 15 -- WASHINGTON - Darline Graham Nordone took the oath of office Tuesday as a United States senator from South Carolina, stepping into a seat her brother held for a quarter century and making history as the first woman to represent the state in the Senate.

no senator had ever been directly succeeded by a sibling.

Nordone's tenure is defined in advance by its expiration. She holds the seat through January, when a winner from South Carolina's special election process takes over. State Republicans have set August 11 as the date for a special primary to select the party's nominee, with a general election to follow. The compressed timeline reflects a party need to lock in a standard-bearer before the legislative calendar shi...