Senator Olympia Snowe, one of the few remaining Republican moderates in Congress, announced on Tuesday that she will not seek re-election to what would be a fourth six-year term.
Snowe's decision will complicate her party's effort to win control of the Senate from President Barack Obama's Democrats in the November 6 elections. Republicans need to pickup at four seats to take the chamber, three if Republicans win the White House.
"After an extraordinary amount of reflection and consideration, I am announcing today that I will not be a candidate for re-election to the United States Senate," Snowe said in a brief statement.
"After 33 years in the Congress this was not an easy decision," Snowe said, adding, "I have no doubt I would have won re-election."
As a moderate, Snowe faced potential challenges for the Republican Senate nomination from the conservative Tea Party movement.