Vice President-elect Joseph Biden will officially step down from his Delaware Senate seat on Jan. 15, ending a Senate career that has spanned more than three decades. Biden secured re-election to the Senate in November, even as he won election as vice president.

Biden’s letter of resignation, addressed to Vice President Dick Cheney, who is President of the Senate, was read on the floor moments ago.

“We all will miss Senator Biden and his many, many years in the Senate. But we look forward to him working arm in arm with Barack Obama for the next eight years,” Senate Majority Leader Harry Reid (D-Nev.) said in remarks on the Senate floor.

Democrat Ted Kaufman, Biden’s former longtime chief of staff, is set to succeed the vice president-elect. He does not plan to stand for election in the 2010 special election that will be held to determine who fills the remaining four years of Biden’s current term.