ABC News' Z. Byron Wolf reports: Democrats don't meet in their special caucus huddle until 5 p.m., when Senate Majority Leader Harry Reid will officially unveil his version of health reform to them. But the Senate is abuzz with activity right now. Vice President Joe Biden has been on the Hill for most of the day, meeting with Reid and working from his own office off the Senate floor. Moderate Democrats who have expressed their reservations with the broad strokes of the legislation, including Sen. Mary Landrieu of Louisiana, Sen. Blanche Lincoln of Arkansas and Sen. Ben Nelson of Nebraska, all just walked into Reid's office. A Reid spokesman said Reid will give the moderates a first: Reid "walking them through the particulars" before he distributes the bill to the rank and file. Reid will need all Democrats to support the bill if he wants to break the first Republican attempt at filibuster, likely to come Saturday. So his special session with the moderates is an attempt to bring them on-board.