At Middlesex, we give our international students the support and assistance they need to succeed at a U.S. college. The individual who signs the affidavit of support becomes the sponsor once the intending immigrant becomes a lawful permanent resident.An Affidavit of Support assures financial responsibility for another person, typically in immigration cases. Form I134, Affidavit of Support. Search Submit Clear. Petitioner: The petitioner must complete an Affidavit of Support Form I-864. The person who signs the Affidavit of Support is also called the "sponsor.