Despite some speculation to the contrary, Weicker said he would not run against Lieberman, a Democrat who ousted him from the Senate in 1988. That, however, didn't stop him from attacking the incumbent.
Speaking at a Rotary Club luncheon, Weicker sharply criticized Lieberman and President Bush over the Iraq war.
"I have seen this country propagandized into war," said Weicker, a Republican-turned-independent. "It's now a second wave of propagandizing, with the president taking the stump, joined by persons like Senator Joe Lieberman."
Lieberman, an early supporter of the war in Iraq, has drawn condemnation from some liberal Democrats in Connecticut for his position and blamed it for his loss in the 2004 Democratic presidential primaries.
Weicker said he disagrees completely with the position Lieberman has taken on the war: "The nation does not need a Democrat to second the president's policy."
Lieberman said in a statement that he is "accustomed to having opponents, and I look forward to putting my record before the Connecticut voters again next year."
Weicker said U.S. troops should leave Iraq in six months to a year. "I support the troops. I do not support the commander in chief," he said.
While Weicker, 74, said he will not challenge Lieberman, he did not entirely rule out returning someday to the Senate seat he held for 18 years.
"You're not going to tell somebody in politics for 32 years you have no interest at all," he said. "I would hope, however, that the Democratic party exercises some choices."
Weicker acquired a reputation as a maverick even before leaving the GOP two years after his stunning loss to Lieberman to form the independent Connecticut Party and win the governor's office.
He said more candidates who are unaffiliated with either major party should seek public office and derided Democrats as "a bunch of wimps" who are as bad as Bush.
"It's a one-party deal. That's what we've come to," he said.