With Hillary Clinton and Bernie Sanders locked in a tight race, either candidate could get a boost from caucus-goers who veer off-script.

Republicans have been demanding an anti-Obama for years—and tonight, they'll begin the process of nominating one.

As the candidates flood the airwaves, they're hoping to convey their connection with "real" Iowans. What comes across is often just the opposite. Plus: This week's ad round-up.

The candidates get in a last word before the Iowa Caucus.