It is pretty simple to tell when someone is "bias" towards something (if they are introducing it in a positive light) and when someone is "bias" against something (if they are introducing it in a negative light.
Here, Senator Hartford is being introduced as a leader (an important and favorable position-positive) and Senator Williams is introduced with the tagline of an investigation into some corruption that he may or may not be involved in (negative). Therefore, the bias is in favor of Senator Hartford.
