UPI POY 2008 - Presidential Campaign (150 images)

Democratic presidential candidate Sen. Barack Obama (IL) uses a PDA as he walks through the halls of Congress in between votes in the Senate on Capitol Hill in Washington on March 13, 2008. (UPI Photo/Roger L. Wollenberg)

Democratic presidential candidate Sen. Barack Obama (D-IL) addresses supporters at Soldiers and Sailors Military Museum and Memorial in the Oakland section of Pittsburgh at the kick off his bus tour of Pennsylvania on March 28, 2008. (UPI Photo/Archie Carpenter)

U.S. President George W. Bush and Republican presumptive presidential nominee Sen. John McCain (R-AZ) shake hands after speaking to the media in the Rose Garden of the White House on March 5, 2008. Bush endorsed McCain's candidacy and pledged to support McCain during the campaign. (UPI Photo/Roger L. Wollenberg)

Presumptive Republican presidential nominee Sen. John McCain (R-AZ) arrives to visit the southern Israeli town of Sderot on March 19, 2008. McCain is in the region as part of congressional delegation with Senators Lindsey Graham (R-SC) and Joe Lieberman (I-CT). (UPI Photo/Uriel Sinai/POOL)