Democratic presidential candidates have clashed on Iraq and over the security of the US since the September 11, 2001, terror attacks.

Mark Warner’s decision to bow out of the early US presidential race leaves a field still crowded with Democrats competing to be the most attractive alternative to front-runner Sen. Hillary Rodham Clinton.

John Kerry easily won New Hampshire’s primary election on Tuesday, overpowering Howard Dean and other rivals for a second-straight victory to establish the four-term senator as the party’s presidential front-runner.