During the hours of testimony on Friday, did anyone ask point blank:
“Did YOU instruct IRS staff to scrutinize conservative 501C4 applicants?”
If the Representatives asking him don't have any evidence to force him to admit it, he'll just deny it. They need to climb the ladder from the low level employees upward. Get the ones who actually turned down the tax exempt status for Tea Party groups to turn over memos and provide testimony against they bosses, then get them to turn on their bosses until you hit the top.
About the only thing you could get from directly asking your question today is the chance to nail him on perjury later.