Barack Obama defeated Hillary Rodham Clinton in the Vermont primary Tuesday, one of two smaller primaries ahead of major contests that Clinton needs to win to keep her hopes alive for the Democratic presidential nomination. The Vermont victory was Obama's 12th straight over the former first lady, who is desperate to rebound later in Ohio and Texas. A fourth primary was in another small Northeastern state, Rhode Island. John McCain moved closer to sealing the Republican presidential nomination, winning Vermont's 17 delegates. That put his magic number - 1,191 - within reach. The Associated Press called the winners based on surveys of voters as they left the polls.