Part of Texas' congressional redistricting map from 2003. The lead plaintiffs in Evenwel v. Abbott are residents of a state Senate district in Texas who say their equal rights to representation are diluted because Texas equalized the districts in population terms and€” not in terms of eligible voters. Harry Cabluck/AP hide caption

itoggle caption Harry Cabluck/AP

Republican presidential candidate Sen. Rand Paul's 10 1/2 hours on the Senate floor were about liberty, the Constitution and the need to stand out in a field of presidential hopefuls. Andrew Harnik/AP hide caption

itoggle caption Andrew Harnik/AP

A young female protester faces down armed police officers at an anti-Vietnam War demonstration outside the 1968 Democratic National Convention in Chicago. Hulton Archive/Getty Images hide caption

itoggle caption Hulton Archive/Getty Images

Senate Minority Leader Harry Reid, D-Nev., (left) and Majority Leader Mitch McConnell, R-Ky., at a ceremony last month at the U.S. Capitol. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

Hillary Clinton is running with all the advantages and challenges of someone who has been in the public eye for more than two decades. Andrew Burton/Getty Images hide caption

itoggle caption Andrew Burton/Getty Images

Sen. Christopher Dodd, D-Conn., left, with then-Senate Minority Leader Tom Daschle at a 1995 news conference on Capitol Hill. Harry Reid took over as leader in 2005 after Daschle unexpectedly lost his re-election. At the time, Reid was unknown to most Americans, but he beat back a challenge Dodd. John Duricka/AP hide caption

itoggle caption John Duricka/AP

Vice President Biden and House Speaker John Boehner wait for President Obama's State of the Union address in front of a joint session of Congress in 2012. As vice president, Biden is also leader of the U.S. Senate, but only gets a vote when senators are evenly divided. Saul Loeb/AP hide caption

itoggle caption Saul Loeb/AP

Former Secretary of State and likely 2016 presidential candidate Hillary Clinton faces the media Tuesday over her use of a private server and email account she used to conduct public business. Richard Drew/AP hide caption

itoggle caption Richard Drew/AP

Protesters filled Wisconsin's state Capitol in Madison on Monday, demonstrating against last weekend's shooting death of Tony Robinson, an unarmed black man. Andy Manis/AP hide caption

itoggle caption Andy Manis/AP