Clinton tackles Obama over security issues

Hillary Clinton sharpened her criticism of Democratic presidential front-runner Barack Obama on national security issues as she and her husband, former President Bill Clinton, waged a campaign blitz in two big states she needs to win to keep her campaign afloat.

Ohio and Texas hold pivotal primaries on Tuesday, along with the smaller states of Vermont and Rhode Island. A total of 370 nominating convention delegates are at stake in the four states.