April 13, 2015PBS NewsHour full episode

Tonight on the program, we examine the race for 2016, as Hillary Clinton and Marco Rubio throw their hats into the presidential ring. Also: Iraq's prime minister to ask U.S. for more support against Islamic State group, a cement alternative absorbs carbon dioxide like a sponge, whether budget cuts and Obamacare confusion is bottlenecking the IRS, and Jordan Spieth's big win at the Masters.