U.S. President-elect Barack Obama resigned his seat in the Senate on Sunday to focus on his transition to the White House, appointing new staff and thanking his home state of Illinois for launching his political career, BBC reported.
"Today, I am ending one journey to begin another," Obama said in a letter to the people of Illinois, describing his job representing them as one of the highest honors of his life.
"I am stepping down as senator to prepare for the responsibilities I will assume as our nation's next president," he said. "But I will never forget, and will forever be grateful to, the men and women of this great state who made my life in public service possible."
Obama's resignation as senator means he will not participate in this week's post-election session on Capitol Hill that could address the ailing economy and struggling auto industry.
Obama's successor in the Senate will be appointed by Illinois Gov. Rod Blagojevich, a Democrat.
Obama, who will be sworn in as president on January 20, grew up in Hawaii and spent part of his childhood in Indonesia. He moved to Illinois as an adult to work as a community organizer.
Obama cited one of his heroes, Abraham Lincoln, who hailed from the same state, when saying his goodbye.
"It was long ago that another son of Illinois left for Washington," Obama wrote.
"A greater man who spoke to a nation far more divided, Abraham Lincoln, said of his home, 'To this place, and the kindness of these people, I owe everything.' Today, I feel the same."
The Democratic president-elect has been assembling his White House team and studying cabinet appointments since beating Republican rival John McCain in the November 4 election.
Obama added three officials to his White House team on Sunday, making his top aide from the Senate a senior adviser and naming two deputies to chief of staff Rahm Emanuel.
His transition office said in a statement that Pete Rouse, who led Obama's staff as an Illinois senator, would join the White House as a senior adviser.
Rouse worked for former Senate Democratic Leader Tom Daschle for 19 years. Daschle, a former South Dakota senator, advised Obama during his presidential campaign and is thought to be in contention for a top post in the new administration.
Obama's office also said Mona Sutphen, a longtime foreign service officer who worked in President Bill Clinton's White House on the National Security Council, and Jim Messina, a former top aide to two U.S. senators, would both serve as deputy chief of staff.
"These individuals are important additions to a team with the experience and ability to help our nation overcome pressing challenges at home and around the world," Obama said in the statement.