Exhibit 23(a) CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM We consent to the incorporation by reference in Registration Statement No. 333-105133 of TXU Corp. on Form S-8 of our report dated June 24, 2004, appearing in this Annual Report on Form 11-K of the TXU Thrift Plan for the year ended December 31, 2003. /s/ DELOITTE & TOUCHE LLP Dallas, Texas June 25, 2004