To assist in providing adequate housing for families of low and moderate income, particularly in suburban and outlying areas, this section is designed to supplement systems of mortgage insurance under other provisions of this chapter by making feasible the insurance of mortgages covering properties in areas where it is not practicable to obtain conformity with many of the requirements essential to the insurance of mortgages on housing in built-up urban areas. The Secretary is authorized, upon application by the mortgagee, to insure, as hereinafter provided, any mortgage (as defined in section
1707 of this title) offered to him which is eligible for insurance as hereinafter provided, and, upon such terms as the Secretary may prescribe, to make commitments for the insuring of such mortgages prior to the date of their execution or disbursement thereon: Provided, That the aggregate amount of principal obligations of all mortgages insured under this section and outstanding at any one time shall not exceed $100,000,000, except that with the approval of the President such aggregate amount may be increased at any time or times by additional amounts aggregating not more than $150,000,000 upon a determination by the President, taking into account the general effect of any such increase upon conditions in the building industry and upon the national economy, that such increase is in the public interest: And provided further, That no mortgage shall be insured under this section after August 2, 1954, except pursuant to a commitment to insure issued on or before such date.