(a) A municipality shall pay into the project account the entire cash local grant-in-aid at the earliest date possible but in any event no later than the date of the application for a progress payment except as may be otherwise approved by the commissioner.

1. (1) A municipality which cannot appropriate and pay the required cash grant-in-aid to the Municipal Urban Renewal Agency from the general or other fund available for current expenses of the municipality without undue hardship, as determined by the commissioner, may request the Municipal Urban Renewal Agency to borrow for and on behalf of the municipality a sum sufficient to provide the amount of the cash grant-in-aid provided the municipality guarantees the payment from municipal sources of the principal and interest on the bonds and notes, assumes and pays all costs involved in the sale of such bonds or notes including legal fees, paying agent fees and all other expenses of the transaction and agrees to make payments to the Municipal Urban Renewal Agency at such appropriate times as will enable the Municipal Urban Renewal Agency to make timely payments on account of the obligation undertaken and arising therefrom.
2. (2) Whenever it is determined that the Municipal Urban Renewal Agency shall borrow the amount of the cash grant-in-aid for and on behalf of the municipality, as above provided, the cooperation agreement between the municipality and the Municipal Urban Renewal Agency shall so provide and the specific obligations of the municipality, in such event shall be stated therein in detail. A cooperation agreement which does not initially so provide may be amended to do so.

(b) Municipal guarantee.