Biden was seen as a possible successor to his father, Democrat Joe Biden, who must resign his Senate seat before being sworn in Jan. 20 as vice president. Delaware's governor will appoint a new senator.
Speculation on Biden's replacement has centered on Lt. Gov. John Carney. He lost the Democratic gubernatorial primary in September to State Treasurer Jack Markell, who is now Delaware's governor-elect. Carney did not immediately return a telephone message Wednesday.
Biden, a captain and military lawyer in the signal unit, said in a statement he has not sought and would not accept an appointment to the Senate, and that he looks forward to returning to his job as attorney general after his service tour.
"I want to thank the people of Delaware for the honor of serving as their attorney general and express my appreciation for their understanding as I fulfill my military obligations," he said in the statement.
The statement may have been a formality, given that an Army spokesman previously was quoted as saying military policy would bar Biden from performing the duties of any elective office while on active duty, and that being the son of a vice president-elect would not lead to his deployment ending early.
Joe Biden was re-elected to the Senate earlier this month but must give up his seat before being sworn in Jan. 20 as vice president. Delaware's governor will appoint a new senator, who would serve for two years until the 2010 election, at which time the younger Biden, notwithstanding Tuesday's statement, could declare his candidacy.
Kate Bailey, a spokeswoman for Democratic Gov. Ruth Ann Minner, declined to say whether Minner and Joe Biden have discussed plans to appoint his successor in the Senate.
While Minner is expected to choose Biden's replacement, there is an outside chance that Democratic Gov.-elect Jack Markell could make the pick. He is scheduled to take the oath of office as governor shortly after midnight on Jan. 20. If Biden were to wait until the last minute to resign his Senate seat, Markell would have a brief window of time to choose a replacement before Biden is sworn in as vice president later that day.
Markell spokesman Joe Rogalsky said Markell is focused on making the transition to governor's office and tackling the significant economic challenges facing Delaware.
"He hasn't thought at all about a possible Senate appointment," Rogalsky said.