The correct answer to this open question is the following.
The rise of social media platforms and increased technology led to increased candidate-centered campaigns in that people in the campaign started to focus more on the candidates, their personalities, their profiles, their charisma, and their contact with followers and citizens.
In the past, the role of the political party had a more specific presence in the campaigns as well as in their platforms. The campaign's teams used to present their platforms and proposals as the main flag during electoral campaigns.
Now, with the advent of social media, most of the time the campaign is centered around the personality and charisma of the candidate and the way he/she can connect to audiences.
The first candidate that really used and exploit social media to reach its audiences was Democrat candidate Barak Obama.