That’s what Connecticut politico Kevin Rennie is reporting:
United States Senator Joseph Lieberman (I-CT) is expected to announce Wednesday that he will not seek a 5th term in 2012, Daily Ructions has learned. Lieberman has invited supporters to an event at the Marriott hotel in Stamford Wednesday afternoon for his announcement.
Cook has Lieberman’s seat as “Lead D” in 2012.
UPDATE: Former Connecticut secretary of state Susan Bysiewicz has already announced she’ll vie for the Democratic nomination for Lieberman’s seat. Her internal polling purportedly shows her ahead of much of the probable field, including Linda McMahon.