Democrat Ned Lamont labeled the three-term Connecticut senator a career politician in lockstep with President Bush on Iraq. Longshot Republican Alan Schlesinger described himself as the only conservative in a race against two liberals, warning GOP voters about Lieberman's mostly Democratic voting record.
Lieberman took the jabs and delivered a few of his own.
"His fingerpointing... is the last thing Washington needs more of," Lieberman said of Lamont, accusing him of running a negative campaign.
Lieberman is seeking another term as a third-party candidate after losing the Democratic primary to Lamont. The senator holds a single-digit lead over Lamont in recent polls. with Schlesinger far behind.
In the first debate since the August primary, Lamont focused on his signature issue — his opposition to the Iraq war. Lieberman is a proponent of the war.
"I'm running against a career politician who says, 'Stay the course,"' Lamont said. "It's time for us now to redeploy our forces."
Lieberman has warned that pulling out U.S. troops too soon would be disastrous, but he also insisted he does not support an open-ended deployment of forces in Iraq.
Schlesinger, recalling Lieberman's public scolding of former President Clinton during the sex scandal involving a White House intern, sniped at Lieberman for being out of Washington as North Korea pursued its nuclear ambitions.
"The question should be why has Joe Lieberman over the last 18 years not been there on this issue," Schlesinger said. "Joe, you had more moral outrage about Mr. Clinton's indiscretions than about North Korea's nuclear proliferation."
He also branded Lieberman part of what he called the "ostrich club" in the Senate.
"They stick their head in the sand and hope something good will come out of it," the Republican said.
Lieberman has won support from some top Republicans and the White House has declined to support Schlesinger, 48, a former mayor and state representative.
Lamont, 52, a wealthy cable TV executive, has tapped more than $10 million of his personal fortune to fund his campaign, adding $2 million as recently as Monday. He cast himself as an outsider who would take on Washington's powerful special interests.
"Right now, we have a situation in Washington that's out of control," he said.
Lamont also found himself on the defensive over his cable TV firm, challenging a Lieberman TV ad that alleges he laid off 68 percent of his work force.
After the Sept. 11 terrorist attacks, Lamont said his firm had to sell off some of its residential systems. Lamont said only about a third of the job losses were due to layoffs. About two-thirds of the job losses were due to workers moving to other companies.
"That ad is absolutely false," complained Lamont.
Shot back Lieberman: "The facts show... that he cut 68 percent of his workers. That is the fact."
Lieberman, 64, stressed his ability to work across party lines to deliver for Connecticut. He criticized Lamont as inexperienced and overly partisan.
"The government is broken, gridlocked by partisanship," he said. "There's too much personal hatred."
Lamont apologized to Lieberman for a controversy last week involving a black leader who accused Lieberman of lying about his civil rights activism during the 1960s. The man later recanted the charge after Lieberman offered proof. Lamont had been at an event receiving a black group's endorsement when the charge was made.
"Senator, I apologize for those comments," Lamont said. Lieberman thanked Lamont for the apology.