; conclusiveness and validity of guarantee (1) Full faith and credit of united states pledged for payment The full faith and credit of the United States is pledged to the payment of a note or other obligation guaranteed under this section. (2) Conclusiveness and validity of guarantee (A) Conclusiveness A guarantee made by the Secretary under this section shall be conclusive evidence of the eligibility of the obligation for the guarantee with respect to principal and interest. (B) Validity The validity of a guarantee made by the Secretary under this section shall be incontestable in the hands of a holder of the guaranteed obligation. (3) Limitation on percentage A guarantee made under this section shall guarantee repayment of 100 percent of the unpaid principal and interest due on the notes or other obligations guaranteed. (h) Limit on outstanding obligations; monitoring use of guarantees (1) Limit on outstanding obligations The total amount of outstanding obligations guaranteed on a cumulative basis by the Secretary under this section may not at any time exceed the greater of— (A) $4,500,000,000; or (B) such higher amount as may be authorized to be appropriated to carry out this section for a fiscal year. (2) Monitoring use of guarantees (A) In general The Secretary shall monitor the use of guarantees under this section by participating jurisdictions. (B) Actions to ensure sufficient authority If the Secretary finds under subparagraph (A) that 50 percent of the aggregate guarantee authority under paragraph (1) has been committed, the Secretary may— (i) provide that a unit of general local government that receives a grant under section 211 may not receive more than $35,000,000 in guarantees under this section