EXHIBIT 15.

Southwestern Public Service Company:

We have made a review, in accordance with standards  established by the American
Institute  of  Certified  Public   Accountants,   of  the  unaudited   condensed
consolidated  interim  financial  information  of  Southwestern  Public  Service
Company and  subsidiaries  for the periods ended  November 30, 1996 and 1995, as
indicated  in our report dated  January 10, 1997;  because we did not perform an
audit, we expressed no opinion on that information.

We are aware  that our  report  referred  to above,  which is  included  in your
Quarterly  Report on Form 10-Q for the  quarter  ended  November  30,  1996,  is
incorporated by reference in Registration  Statement Nos. 33-53171 and 333-05199
on Form S-3,  Registration  Statement No. 33-64951 on Form S-4, and Registration
Statement Nos. 33-27452 and 33-57869 on Form S-8.

We are also aware that the aforementioned report,  pursuant to Rule 436(c) under
the  Securities  Act of  1933,  is not  considered  a part  of the  Registration
Statement  prepared  or  certified  by an  accountant  or a report  prepared  or
certified by an accountant within the meaning of Sections 7 and 11 of that Act.


Deloitte & Touche LLP

January 10, 1997
Dallas, Texas