Delaware ? Edward “Ted” Kaufman, a former aide to Sen. Joe Biden, was named Monday by Delaware Gov. Ruth Ann Minner to fill the Senate seat Biden is leaving for the vice presidency.

Kaufman, co-chair of Biden’s transition team and an Obama-Biden transition project advisory board member, plans to serve until the 2010 election, when a new senator is elected. He said he is comfortable stepping down after two years in office.

Speculation on Biden’s successor had centered in recent weeks on his son, Attorney General Beau Biden. But last week the younger Biden announced that he planned to fulfill his National Guard duties and wouldn’t accept an appointment to his father’s U.S. Senate seat.

Beau Biden is a prosecutor for the 261st Signal Brigade, which left for Iraq last week. The unit is due back in September 2009, in time for Biden to run for his father’s Senate seat.

The elder Biden said in a statement, “It is no secret that I believe my son, Attorney General Beau Biden, would make a great United States Senator just as I believe he has been a great attorney general. But Beau has made it clear from the moment he entered public life that any office he sought he would earn on his own.”