Friends of U.S. Senator Joseph Lieberman of Connecticut say he will announce Wednesday that he will retire from the Senate in 2012 instead of seeking a fifth term in office.
Lieberman is expected to announce his decision at an event in Stamford, Connecticut.
The 68-year-old Lieberman represented the state as a Democrat for 18 years. In 2006, Lieberman was re-elected to the Senate as an independent, after losing the Democratic primary because of his support for the U.S.-led invasion of Iraq.
In the years since, Lieberman usually has voted with Democrats in the Senate. But in 2008, he angered many Democrats by campaigning vigorously for Republican presidential candidate John McCain, who lost the election to the Democratic candidate, Barack Obama.
Democrats in the Senate allowed Lieberman to keep his chairmanship of the Homeland Security Committee, despite his support for McCain. Lieberman, however, had to step down as the head of an environmental committee.
Lieberman was Vice President Al Gore's running mate in 2000 on the Democratic ticket for the presidency. In 2004, he mounted his own failed bid for the presidency.
Some information for this report was provided by AP, AFP and Reuters.