Who is allowed to administer the oath of office?

the oath of office may be administered by any notary public or by any other officer authorized by Statute to administer oaths

A person authorized to administer oaths by the laws of the United States, including section 2903 of title 5, or of a State or territory, or an officer, civil or military, holding a commission under the United States, or any officer or employee of the Postal Service designated by the Board may administer and certify the oath of office.