DeVos, a billionaire charter school advocate, was called "incompetent" and an "amateur" by Democrats during their all-nighter. Two Republicans have vowed to vote against her confirmation, likely splitting the vote 50-50.
Prior to Tuesday's vote, there have been 244 occasions on which the vice president has had to break a Senate tie. The last time was in 2008, when Dick Cheney broke a tie on a budget resolution. Joe Biden never cast a tie-breaking vote.
So while DeVos is likely to be confirmed, the rare tie-breaking vote makes her path to the Cabinet unusually rocky.