Exhibit 4(a)(iii)


                              ASSUMPTION AGREEMENT

     ASSUMPTION AGREEMENT (this "Agreement"), dated as of April 7, 2000, is by
TNP Enterprises, Inc., a Texas corporation (the "Company").

                               W I T N E S S E T H

     WHEREAS, ST Acquisition Corp., a Texas corporation ("Acquisition"), has
heretofore executed and delivered to CIBC Inc., CIBC World Markets Corp., Chase
Securities, Continental Casualty Company and Laurel Hill Capital Partners LLC
(the "Purchasers") a purchase agreement (the "Purchase Agreement"), dated as of
April 7, 2000, providing for the terms pursuant to which the Purchasers have
purchased 100,000 shares of Senior Redeemable Preferred Stock (the "Shares") of
Acquisition;

     WHEREAS, Acquisition has heretofore executed and delivered to the
Purchasers a registration rights agreement (the "Registration Rights
Agreement"), dated as of April 7, 2000, providing for the registration of the
Shares and the Exchange Shares (as defined in the Registration Rights Agreement)
of Acquisition under the Securities Act of 1933, as amended;

     WHEREAS, Acquisition has been merged with and into the Company (the
"Merger"); and

     WHEREAS, pursuant to the Purchase Agreement and the Registration Rights
Agreement, the Company upon consummation of the Merger is required to assume all
of the obligations of Acquisition under the Purchase Agreement and the
Registration Rights Agreement and to execute and deliver this Agreement
concurrently with the Merger.

     NOW, THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the Company
covenants and agrees for the benefit of the Purchasers as follows:

     1. ASSUMPTION. The Company hereby agrees to assume all of the obligations
of Acquisition and all of its own obligations under the Purchase Agreement and
the Registration Rights Agreement.

     2. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK,
WITHOUT REGARD TO THE CHOICE OF LAW PRINCIPLES THEREOF, SHALL GOVERN AND BE USED
TO CONSTRUE THIS AGREEMENT.

     3. EFFECT OF HEADINGS. The Section headings herein are for convenience only
and shall not affect the construction hereof.


                                      -2-


     IN WITNESS WHEREOF, the Company has caused this Agreement to be duly
executed and delivered as of the date first above written, which is the date of
the Merger.


                                       TNP ENTERPRISES, INC.



                                       By:
                                          -----------------------------------
                                              Name:
                                              Title: