But it was the Republican candidate, Alan Schlesinger - the lawyer and former mayor of Derby the polls have consistently shown languishing in the single-digit netherworld - who captivated the crowd gathered for the debate inside the Stamford hotel ballroom.
Schlesinger, who suggested that Bush and other Republican leaders were not-so-secretly backing Lieberman because of his support for the White House's war in Iraq, performed like an athlete feeling loose before the big game.
He bounced and weaved throughout the hourlong encounter, getting off the best one-liners and practically shouting that he wasn't dead yet.
"These two are about who gets the best deck chairs to watch it go down," Schlesinger said after Lamont blasted Lieberman for what he called Lieberman's flip-flopping on whether Social Security should be privatized, a charge Lieberman adamantly denied.
"Joe, you want to put an I.O.U. in a lockbox," he said, referring to former Democratic presidential candidate Al Gore's buzzword in the Social Security debate. "I want a check."
Schlesinger also directly addressed the senator after a similar tussle over health care policy, proclaiming that "Joe Lieberman is against all these issues we as moderates and conservatives hold dear."
Asked about North Korea's apparent test of a nuclear weapon, he sent more titters across the auditorium by going right after Lieberman, telling that the senator that, "Joe, you had more moral outrage at President Clinton's indiscretions."
Lieberman even acknowledged that he was surprised by Schlesinger's performance, saying he hadn't expected to be attacked from both sides of the podium.
"Wow," he said, after one of the Republican's zingers. "OK."
George C. Jepsen, the former state Senate majority leader, Democratic gubernatorial candidate, and Democratic state chairman who is Ned Lamont's campaign chairman, couldn't contain his glee at the prospect of an energized Schlesinger pulling Republican votes away from Lieberman, whom pundits have dubbed the "defacto Republican candidate."
"This debate was very, very good for Al Schlesinger," Jepsen said, calling him a "bright, capable person."