From left, Sen. Jeff Flake, R-Ariz., Sen. Chuck Schumer, D-NY, Sen. John McCain, R-Ariz., and Sen. Michael Bennett, D-Colo, arrive at a news conference after their tour of the Mexico border with the United States on Wednesday in Nogales, Ariz. The senators are part of the "Gang of Eight," a larger group of legislators collaborating on changes to immigration. Ross D. Franklin/AP hide caption
Sen. Carl Levin has been a vocal advocate for transparency in political ad spending. Alex Wong/Getty Images hide caption
The new rules' would reduce harmful emissions, the EPA says. David Paul Morris/Getty Images hide caption
House Speaker John Boehner, R-Ohio, left, performs a mock swearing in for Rep. Don Young, R-Alaska, on Jan. 3, as the 113th Congress began. On Friday, Boehner condemned Young, the second most senior Republican in the House, for using the term "wetbacks," which Boehner called "offensive and beneath the dignity of the office he holds." Charles Dharapak/AP hide caption
Same-sex wedding cake topper figurines at Cake and Art in 2008 in West Hollywood, Calif. David McNew/Getty Images hide caption
Police stand guard in front of the U.S. Supreme Court on Wednesday as the justices hear arguments on the constitutionality of the federal Defense of Marriage Act. Jewel Samad/AFP/Getty Images hide caption
Voters line up into the night outside a Miami polling station, some waiting for hours to vote in the 2012 presidential election. Wilfredo Lee/AP hide caption
A woman views a Mitt Romney campaign ad in September, a month after the launch of an online government database that is supposed to make it easier for the public to see what political ads air in big markets, and how much is spent on them. Karen Bleier/AFP/Getty Images hide caption
This artist rendering shows Paul Clement (second from left) with Solicitor General Donald B. Verrilli Jr. (seated, right), addressing the Supreme Court on Wednesday. Justices pictured are (from left) Sonia Sotomayor, Stephen Breyer, Clarence Thomas, Antonin Scalia, Chief Justice John Roberts, Anthony Kennedy, Ruth Bader Ginsburg, Samuel Alito and Elena Kagan. Dana Verkouteren/AP hide caption
Ashley Judd watches Kentucky play Vanderbilt during the first half of an NCAA college basketball game at the Southeastern Conference tournament on March 15 in Nashville. Dave Martin/AP hide caption
This artist rendering shows Roberta Kaplan, attorney for plaintiff Edith Windsor, addressing the Supreme Court during arguments on the Defense of Marriage Act on Wednesday. Dana Verkouteren/AP hide caption
Demonstrators gathered again outside the Supreme Court Wednesday as the time approached for another case to be heard about issues related to same-sex marriage. Chip Somodevilla/Getty Images hide caption