Simplify the following text for a Grade 6 native English-speaking person.
Original: However , the amendment states of the appointee that if `` before taking his seat he ceases to be a member of that party ... he shall be deemed not to have been so chosen or appointed '' .
Simplified: However , the change also says that if the new Senator `` before taking his seat he ceases to be a member of that party ... he shall be deemed not to have been so chosen or appointed '' .