The Secretary, acting through the Service, may enter into an agreement with an Indian tribe, tribal organization, or urban Indian organization which provides for the receipt and processing of applications for medical assistance under title XIX of the Social Security Act [
42 U.S.C.
1396 et seq.] and benefits under title XVIII of the Social Security Act [
42 U.S.C.
1395 et seq.] at a Service facility or a health care facility administered by such tribe or organization pursuant to a contract under the Indian Self-Determination Act [
25 U.S.C.
450f et seq.].