To carry out the purposes of section
1721 of this title, the Government National Mortgage Association may enter into new commitments to issue guarantees of securities based on or backed by mortgages insured under this section, not exceeding $300,000,000,000. The amount of authority provided under the preceding sentence to enter into new commitments to issue guarantees is in addition to any amount of authority to make new commitments to issue guarantees that is provided to the Association under any other provision of law.