HOUSTON — Jose Rivera holds a sign in support of Democratic presidential hopeful Sen. Barack Obama of Illinois as he watches him speak during a primary campaign rally at the Toyota Center, Feb. 19, 2008. After winning last week's Potomac Primaries, Obama is facing off with rival contender Sen. Hillary Clinton of New York to secure primary wins in Hawaii and Wisconsin. The Texas presidential primary is on March 4. (Photo by Dave Einsel/Getty Images)
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