WASHINGTON (Reuters) - U.S. Representative Jim Clyburn of South Carolina, the No. 3 Democrat in the House and a prominent African-American leader, will endorse Democratic presidential candidate Hillary Clinton on Friday, NBC News reported on Thursday. The endorsement comes ahead of the Feb. 27 Democratic primary in South Carolina, where more than half of the voters are expected to be African-Americans.  (Reporting by Eric Beech; Editing by Eric Walsh) This article was funded in part by SAP. It was independently created by the Reuters editorial staff. SAP had no editorial involvement in its creation or production.