THE FACTS: Obama acknowledges that over nearly eight years in the Illinois Senate, he voted "present" 129 times. That was out of roughly 4,000 votes he cast, so those "presents" amounted to about one of every 31 votes in his legislative career.
Illinois legislators often vote "present" and for a wide variety of reasons. Sometimes blocs of lawmakers do it as a protest in some dispute over rules and procedures. Obama was often joined in his "present" votes by 10 or 20 other senators.
In other cases, lawmakers do it to signal objections to the details of a measure that they support in principle. They also use "present" votes as strategic moves to defeat legislation or, of course, simply to avoid taking a firm position.
Clinton highlights several of Obama's "present" votes that she considers questionable.
Several involve abortion -- a ban on certain late-pregnancy abortions, a requirement that a minor's parents be notified and restrictions on a type of abortion where the fetus sometimes survives for short periods.
"A woman's right to choose ... demands a leader who will stand up and protect it," said one Clinton campaign mailer.
But the Illinois Planned Parenthood Council says Obama's "present" votes were actually part of a careful strategy to prevent those restrictions from passing.
President Pam Sutherland said the group feared several senators were going to vote "yes" on the legislation because of attacks from Republicans over their past opposition. Sutherland says she approached Obama and convinced him to vote "present" so that the wavering senators would do the same. For their purposes, a "present" was as good as an outright "no" because it kept the bills from reaching the majority needed to pass.
Clinton also points out that Obama was the lone "present" vote on legislation allowing the victims of rape and other sex crimes to have their court records sealed. Obama explains now that he had questions about its constitutionality, although the law has never been struck down by the courts.
Neither the Illinois Coalition Against Sexual Assault nor the House sponsor of the legislation faults Obama for his vote. Former state representative Lauren Beth Gash, who supports Obama for president, said she ultimately disagreed with his constitutional concerns but that Obama raised legitimate questions and was acting on principle.
Obama also voted "present" on legislation making it easier to send juveniles to adult court. He said in debate that he felt the measure violated an agreement, reached after an overhaul of the juvenile justice system a year earlier, to wait on further changes until the new system had been reviewed.
But he did not explain why he wasn't simply voting "no."