WASHINGTON — IRS Commissioner John Koskinen expressed regret to Congress on Wednesday for his agency’s past mistreatment of Tea Party groups, but said he has cooperated with congressional investigators and does not deserve to be impeached.

The IRS chief made the remarks at a House Judiciary Committee hearing on a drive by hard-line conservatives to oust Koskinen. Their impeachment resolution accuses him of lying to lawmakers, ignoring subpoenas and overseeing an agency that destroyed e-mails as Congress investigated how the IRS subjected Tea Party groups seeking tax exemptions to harsh investigations years ago.

The agency has apologized for its actions and Koskinen has said he’s done nothing wrong. Government investigators have found no evidence that Koskinen or the IRS purposely destroyed evidence or that the agency’s actions were politically motivated.

“I did nothing to impede the operation of the Congress,” Koskinen, speaking under oath, told the lawmakers.

Besides solid opposition from Democrats, the push has divided Republicans, won no backing from GOP leaders and has no chance of garnering the votes Congress would need to oust him.

Committee Chairman Bob Goodlatte, R-Va., said the IRS engaged in “a political plan to silence the voices of groups representing millions of Americans.” He said Koskinen is facing “very serious allegations.”

But Rep. John Conyers of Michigan, the panel’s top Democrat, said Republicans were engaged in “partisan attacks cloaked in the impeachment process” that he said “are doomed from the start.”