Balz Rucker, Washington Post The Republican presidential candidates squabbled over spending, leadership, national security and military service here Saturday night, with Rick Santorum thrown on the defensive over his record in Congress and front-runner Mitt Romney gliding largely unscathed through the forum.Romney and Santorum clashed early over what attributes would make the better president. Santorum charged that the nation doesnrsquo;t need a CEO as president mdash; a knock on Romneyrsquo;s private-sector experience.