(a) The authority is authorized to provide for the issuance of refunding obligations for the purpose of refunding any obligations then outstanding which shall have been issued under this subpart, including the payment of any redemption premium thereon and any interest accrued or to accrue to the date of redemption of such obligations and, if deemed advisable by the authority, for any corporate purpose of the authority provided for in this subpart, except to the extent that the issuance of any such refunding obligations is limited or made subject to conditions under any resolution, trust indenture, or other agreement with holders of outstanding obligations of the authority. The issuance of such obligations, the maturities and other details thereof, the rights of the holders thereof, and the rights, duties, and obligations of the authority in respect thereof shall be governed by the provisions of this subpart which relate to the issuance of obligations, insofar as such provisions may be appropriate.

(b) Such refunding obligations may be sold or exchanged for outstanding obligations issued under this subpart; and, if sold, their proceeds may be applied, in addition to any other authorized purposes, to the purchase, redemption, or payment of such outstanding obligations. Pending the application of the proceeds of any such refunding obligations together with any other available funds to the payment of:

(1) The principal, accrued interest, and any redemption premium on the obligations being refunded;

(2) Any interest on such refunding obligations, if so provided or permitted in the resolution authorizing the issuance of such refunding obligations or in the trust indenture securing them; and

(3) Any expenses in connection with such refunding;

such proceeds may be invested in direct obligations of, or obligations the principal of which and the interest on which are unconditionally guaranteed by, the United States which shall mature or which shall be subject to redemption by their holders at the option of such holders, not later than the respective dates when the proceeds, together with the interest accruing thereon, will be required for the purposes intended.