The final vote was 255-67, Republicans voting 238-2 for the contempt resolution, Democrats voting 17-65 (1 present) against, and 108 Democrats not voting.
The nonvoting was completely intentional: the Congressional Black Caucus urged Democrats not to vote and Minority Leader Pelosi joined in. Politico says:
Reps. Jim Clyburn (S.C.) and John Lewis (Ga.), two veteran black lawmakers, gave impassioned speeches to their Democratic colleagues on Thursday asking that they demonstrate their support for Holder. Holder is the first African-American to serve as attorney general.The nice thing about this tactic is that it is a suitable response to the situation the Democrats found themselves in. The contempt resolution stank of politics (the inquiry was not into the Fast and Furious operation per se, which began during the Bush Administration, but Holder's response to the scandal), so Democratic opposition was a natural response. However, the National Rifle Association was "scoring" the vote, so a "nay" vote would downgrade Democrats on the NRA's year-end evaluation. Nonvoting solves both problems: it expresses not just disapproval, but disrespect for the proposal of the majority party and the legitimacy of the proceedings. At the same time, it gives conflicted members some latitude for how they explain their position. And, depending on how the NRA scores nonvoting on this roll call, it may enable them to avoid a downgrade on their annual NRA score.
There is a general term for collective, strategic nonvoting: a disappearing quorum. During the 19th century, it was a common form of obstruction in the U.S. House, as the minority party would attempt to halt the chamber's proceedings by withholding their votes in the hopes that the majority party could not muster enough votes to form a quorum (i.e. a sufficient number of members to make decisions). More recently, we have seen this in state legislatures: Texas in 2003 and Wisconsin in 2011. In both cases, legislators in minority party fled across state lines to break a quorum without being dragged back to the chamber by state police.
Even when the minority party could not break a quorum, its members can still refuse to vote en masse, and in doing so put the entire responsibility for the passage of some measure on the majority party. In the case of this resolution, the tactic would seem to fit the case.