50 years of Walter Cronkite's America This is Face the Nation: April 15 Today on Face the Nation: Scandal in Colombia with Rep. Darrell Issa, R-Calif., Campaign 2012 and foreign policy with Sen. John McCain, R-Ariz., the Buffett Rule and the economy with Treasury Secretary Tim Geithner and a panel looks at the Trayvon Martin case. Plus, a politics roundtable examines the War on Women in 2012.