WASHINGTON — The ousted head of the Internal Revenue Service apologized to Congress on Friday for his agency's tougher treatment of tea party and other conservative groups seeking tax-exempt status. He said they resulted from a misguided effort to handle a flood of applications, not political bias.

"I want to apologize on behalf of the Internal Revenue Service for the mistakes that we made and the poor service we provided," Steven Miller, who has been acting IRS commissioner, told the House Ways and Means Committee as the panel held Congress' first hearing on the episode. "The affected organizations and the American public deserve better. Partisanship and even the perception of partisanship have no place at the Internal Revenue Service."

At a hearing that saw lawmakers from both parties harshly criticize his agency, Miller conceded that "foolish mistakes were made" by IRS officials trying to handle a flood of groups seeking tax-exempt status. He said the process that resulted in conservatives being targeted, "while intolerable, was a mistake and not an act of partisanship."