Colleagues of Sen. Robert Byrd of West Virginia mourned his death as family and friends planned his funeral.

Byrd, the longest-serving member of the U.S. Congress, died Monday at the age of 92.

Under West Virginia law, the state's popular two-term Democratic governor, Joe Manchin, has the power to appoint Byrd's successor. Manchin is expected to name a fellow member of his party to succeed Byrd, who was also a Democrat, thereby keeping a total of 59 Democrats in the Senate.

There are questions, however, regarding exactly how long Byrd's appointed successor can serve before another election is held....