Accuse Koskinen of obstructing investigation of agency Tea-Party targetingRepublicans on House Oversight Committee on Monday called on President Obama to oust Internal Revenue Service Commissioner John Koskinen for obstructing the committee’s investigation into the tax agency’s targeting of conservative groups. House Oversight Committee Chairman Jason Chaffetz said the committee was actively considering contempt charges and impeachment proceedings against Mr. Koskinen in the event the president does not remove him from office. “Mr. Koskinen should no longer be the IRS Commissioner. We have asked the president to remove Mr. Koskinen from office,” Mr. Chaffetz said at a Capitol Hill press conference,...