Answer:
a trustee
Step-by-step explanation:
A trustee representation refers to a situation where people in a particular constituency choose their representative in parliament. The people entrust the person they choose with the duty of making significant decisions on their behalf.
As such, the representative acts as the trustee of the people in all their matters at both the local and national scene. As such, the trustee has the mandate to make decisions on behalf of the people; he can then forego the immediate interest of his constituents in favor of the national interest.
Since the senator is a trustee representative of the people and has the power to decide on behalf of the people, he can vote according to his conscience rather than interest of the people.