Fine Gael leader Simon Harris has said he did not meet his own standards, let alone anyone else's, during a meeting with disability care worker Charlotte Fallon in Kanturk, Co Cork last Friday.
Mr Harris said he "came up short" and let himself down, adding that he was "deeply annoyed with myself".
Speaking on RTÉ's Today with Claire Byrne, the Fine Gael leader, who has a brother with autism, said he is "passionate" about disability services.
"I let myself down. I'm deeply annoyed with myself, and there's no one more annoyed with me than me, and particularly on an issue that I feel incredibly passionate about," he said.
"I mean, I have been that 16-year-old teenager who's watched my own mother cry with frustration at being a mother of a child with special educational needs, I know what it's like.
"I know what it's like to be in a family where you feel isolated, where you feel let down, where you fight for services. And, on that issue, of all issues, I am so passionate about it."
Mr Harris said he spoke to Ms Fallon the next day and that he would not make excuses for his actions because that would "take away from the point".
He said he does not think it would be fair for people to judge him on a 40 second interaction on a Friday evening.
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"I think they'll judge me on my record," he said.
"They'll judge me on what I'm going to do over the next five years, what I want to do, what Fine Gael wants to do, and the plans that we've put forward to, for once and for all, fix and rectify disability services.
"That is my burning desire. It's something that I've prioritised since becoming Taoiseach."
Additional reporting PA
