Portman said he finds it hard to believe that a couple of "rogue agents" in Cincinnati were responsible for the conservative targeting and that it was done as an efficiency measure to handle a large number of applications, as was initially suggested.

NPR: Ohio Congressmen On IRS: 'How High Up Did It Go?'

The left was targeting conservative groups and donors well before the Supreme Court's 2010 ruling on independent political expenditures by corporations.

WSJ: Strassel: Conservatives Became Targets in 2008

The group she leads is under investigation for targeting conservative groups.

NPR: With White House Bogged Down By Scandal, GOP Looks For Boost