Answer:
a Jackson supporter.
Step-by-step explanation:
This statement shows that William Marcy was a supporter of Andrew Jackson's policies. Spoils in this context means earned benefits as Andrew Jackson rewarded his supporters with government jobs. Marcy was actually defending one of Jackson's appointments when he made this statement.
So marcy is obviously a supporter because he is obviously trying to say that those who supported Andrew Jackson should be the ones to benefit from his administration.