Lieberman, is trying to avoid being tossed aside by his own state party - which supported him as its vice presidential candidate in 2000 - in favor of Lamont, a wealthy Greenwich businessman who emerged as a serious contender through his strong anti-war views.
The winner of the primary election would move on to November's general election as the party standard bearer.
After establishing a hefty lead in the week leading up to the primary battle, Lieberman had closed some of the gap with Lamont by today.
Lieberman's campaign manager, Sean Smith, told the Associated Press today that political opponents were behind the hacking.
"If Ned Lamont has a backbone in his body, he will call on these people to cease and desist," he said, according to the AP.
Lamont, asked earlier today by the same news organization, said the accusation was, "just another scurrilous charge."