Presidential Primaries

Campaign posters for Democratic presidential candidates Senator Hillary Clinton and Senator Barack Obama outside a polling place in San Antonio, Texas Photograph: Scott Olson/Getty

Poll workers help a man vote at Ross County Senior Center in Chillicothe, Ohio Photograph: Eric Thayer/Getty

Democratic presidential hopeful Barack Obama and his wife Michelle arrive on stage during a election night rally in San Antonio, Texas. Obama won the Vermont primary for his 12th straight victory in one month's time, and he and rival Hillary Rodham Clinton are locked in a tight race in the Texas primary Photograph: Rick Bowmer/AP

Barack Obama speaking at the election night rally in San Antonio, Texas Photograph: Emmanuel Dunand/AFP

Barack Obama lifts a baby while greeting supporters after speaking at an election night rally in San Antonio, Texas Photograph: Shawn Thew/EPA

Republican presidential hopeful Senetor John McCain reads over his election night speech in his hotel suite in Dallas, Texas Photograph: Stephan Savoia/AP

Spokeswoman Brooke Buchanan brushes the hair of John McCain, as he flies between campaign stops in San Antonio and Houston Photograph: Gerald Herbert/AP

Republican presidential hopeful John McCain walks from his hotel suite to his election night rally with his wife Cindy and their daughter Megan in Dallas, Texas. McCain clinched the Republican presidential nomination Tuesday Photograph: Stephan Savoia/AP

Reporters work on their laptops in a men's bathroom as Democratic presidential hopeful Hillary Clinton speaks during a campaign rally at the Burger Activity Center in Austin, Texas Photograph: Justin Sullivan/Getty

Hillary Clinton during a primary election night party at The Columbus Athenaeum, Ohio, Texas Photograph: Eric Thayer/Getty

Hillary Clinton greets supporters as she celebrates her projected wins in the Ohio and Texas primaries in Columbus, Ohio Photograph: Robyn Beck/AFP

Felipe Bravo is dressed only in only underwear and Hillary Clinton stickers as he campaigns across the street from the Palmer Pavillion in McAllen, Texas Photograph: Alex Jones/AP