Hillary Clinton and Bernie Sanders finally face off
The shadow boxing that Hillary Clinton and Bernie Sanders have played at for months -- they've barely mentioned each other on the campaign trail -- will give way to more direct jabs Tuesday night.

That's when the two rivals line up on stage at the first Democratic debate of the 2016 campaign, sponsored by CNN and Facebook. The encounter will provide a crucial opportunity for Clinton and Sanders -- the leading Democratic contenders -- to contrast their personalities, experience and approach to the key issues in the campaign.

Though Clinton and Sanders have rarely mentioned each other's names, they are clearly reacting to each other and their rival's potential weaknesses. Sanders took aim at Clinton's Wall Street record and Iraq vote over the weekend; she put him on the defensive on guns and his poor standing with minority voters.

Until now, they have each had good reason for avoiding full contact with the other. Clinton hasn't wanted to elevate Sanders and his surprisingly strong poll numbers, while Sanders has wanted to maintain his untraditional, above-the-fray image.