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. "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, Reuters reported.