1: "Debate disaster spells the end for Biden's campaign."

2: "Harris steps in to fill the void."

3: "Underdog Harris gains momentum."

4: "Biden's missteps propel Harris forward."

5: "New battle lines drawn in Democratic race."

6: "Harris emerges as frontrunner."

7: "Can Harris maintain her lead?"

8: "Biden's downfall, Harris's rise."

9: "The Democratic primary heats up."