Who is Paul Ryan?

Lois Lerner, the head of the tax-exempt organizations division is placed on leave after scandal. Sen. Chuck Grassley, R-Iowa, says she was asked to resign, but refused. Ken Corbin has been named to take over her department. Gayle King reports.

Lois Lerner, head of the tax-exempt organizations division of the IRS, drew sharp criticism from Republican lawmakers after she invoked her Fifth Amendment right in a House hearing -- after she briefly testified on her own behalf. Norah O'Donnell reports.

In a wide-ranging national security speech, the president will address controversial drone strikes and transparency around their use. Major Garrett reports.

In an online video, ex-congressman Anthony Weiner says he's going to run for NYC mayor. Weiner resigned from Congress after admitting he sent lewd pictures of himself to several women via Twitter. Jim Axelrod reports on Weiner's decision.

Sen. Tom Coburn, R-Okla., talks to the "CBS This Morning" co-hosts about the tornado disaster in his state and how he thinks the federal government should help.

President Obama addressed the nation about the destructive tornado that struck Oklahoma and promised federal aid to help them rebuild their lives.