Former Internal Revenue Service Commissioner Douglas Shulman said that he was "not personally responsible" for the agency's practice of placing elevated scrutiny on conservative groups that applied for nonprofit status, but that he regrets it occurred during his tenure.

"I certainly am not personally responsible for creating a list that had inappropriate criteria on it. What I know, with the full facts that are out, is from the inspector general's report, which doesn't say I'm responsible for that," Shulman said during a Senate Finance Committee hearing Tuesday. "With that said, this happened on my watch and I very much regret that it happened on my watch."

Shulman, who served as IRS commissioner from 2008 to 2012, appeared before the Senate panel with outgoing Acting Commissioner Steven Miller and Treasury Inspector General J. Russell George on Tuesday. Both Shulman and Miller have said that the agency acted inappropriately in how it reviewed groups applying for tax-exempt status.