The dual-code international is thought to have been offered the job of backs coach of the Blues, where he had a brief spell as a player from 2002-04, but has no wish to leave his role as assistant coach of the Super League champions.
Harris has not ruled out a return to the 15-man code in the future but Press Association Sport understands he feels now is not the right time.
The former Leeds and Bradford captain, who has also fielded interest from other Super League clubs, is highly regarded at Wigan, where he recently extended his contract until the end of 2015.
Harris will be back in south Wales on Sunday when Wales play their final group match of the World Cup against the Cook Islands in Neath.
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