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 May 31,  1996 and  1995,  as
indicated  in our report  dated  July 12,  1996;  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  May  31,  1996,  is
incorporated  by reference  in Amendment  No. 1 to  Registration  Statement  No.
33-53171 on Form S-3,  Registration  Statement  Nos.  333-05199 and 333-05289 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

July 12, 1996
Dallas, Texas