Host Michel Martin looks into why some non-profits are tax exempt, and how something like the recent IRS flap could happen. She speaks with David Cay Johnston, a columnist for Tax Analysts and reporter Brentin Mock of Colorlines.com.

Some political columnists say President Obama needs to exercise more "leadership" to bend a divided Congress to his will. But congressional Republicans have little incentive to cooperate with the president. And the more he "leads," the harder it may be for them to follow.

Prayers said before meetings of the town board in Greece, N.Y., have predominantly been Christian. A lower court ruled that officials hadn't done enough to seek out prayers from other faiths. That violates the Constitution's Establishment Clause, the court said. Now the Supreme Court will weigh in.

Whether it's Richard Nixon's resignation or Bill Clinton's impeachment, presidents tend to have a tough time during the back half of an eight-year presidency.

Controversies dominated this past week's political headlines, leaving the Obama White House on the defensive, trying to contain any lasting damage. Host Rachel Martin talks with NPR's Mara Liasson.