Former White House press secretary Robert Gibbs on Monday pushed back at House Oversight Committee Chairman Darrell Issa’s (R-Calif.) claims that top officials from the IRS’s Washington, D.C. office directed the targeting of conservative groups, calling the allegations unsubstantiated and “shameful.” “Republicans are on the verge of overplaying their hand publicly and the American people will quickly lose interest on their side in this,” Gibbs said on MSNBC’s “Morning Joe.” “They want to see the IRS cleaned up, but they understand that Darrell Issa is doing nothing more than politicizing this event. To throw around the words ‘liar’ and ‘perjury’...