With only three days left to reverse the course of the Democratic primary race, Senator Joseph I. Lieberman is scaling back on the ambitious ground operation that his supporters had hoped would pull him past his challenger, Ned Lamont, in Tuesday’s election, people affiliated with the campaign said. In East Hartford on Friday, Senator Joseph I. Lieberman played down poll results. Mr. Lieberman, slipping badly in recent polls, still has solid organizational support. Major unions are planning phone banks on his behalf. Firefighters are taking the day off to drive older voters to polling stations. Black churches are distributing literature...