He’s already done so.
If he were to try and deny it, each time he is accused, that is all he’d do with his time, because the Dems have, basically, professional accusers ready to do a hit on any targets dangerous to them, an endless supply of them.
And, each time he denied it, the denial would look less credible, regardless of the truth.
That the Perry supporters are so desperately eager to pimp a smear against a Conservative in the vain hope it will save their candidate tells us all we need to know about their candidate.