House Oversight Committee Chairman Jason Chaffetz has introduced articles of impeachment against IRS Commissioner John Koskinen.

The IRS targeted conservative groups during the 2012 presidential campaign, delaying by months or even years requests for tax-exempt status.

“Mr. Koskinen was not at the IRS during the targeting, but the former Freddie Mac executive has become the single greatest hurdle to public accountability. He was touted as a reformer in his 2013 confirmation hearings. Instead he has helped the Administration stonewall Congress’s investigation. Mr. Chaffetz’s four articles of impeachment assert that Mr. Koskinen ‘engaged in a pattern of conduct that is incompatible with his duties as an Officer of the United States,’ ” the Wall Street Journal wrote.