Obama and Clinton head for crucial Democratic nomination showdowns

Washington: Hillary Rodham Clinton struggled to salvage her faltering campaign going into crucial nomination showdowns on Tuesday as front-runner Barack Obama set his sights on ending his rival's bid for the Democratic presidential nomination.

Four states vote on Tuesday, but the focus is on races in the big states of Texas and Ohio where the former first lady made a concerted bid of Sunday for votes. She desperately needs wins in both states to salvage her once-powerful bid to become the US's first female president and halt Obama's momentum following his streak of 11 consecutive wins since the February 5 Super Tuesday races.

Recent polls show Clinton retains a lead, albeit a narrowing one, in Ohio, where residents have been hard hit by the US's economic troubles. In Texas, her once formidable lead has all but vanished and the race is now seen as a dead heat. A total of 370 delegates are at state in the four races, including Vermont and Rhode Island.

Neck-deep in a campaign marked by feuding and acrimony, Clinton sharpened her attacks on Obama, targeting his foreign policy and national security experience while appealing to voters in Ohio with a message of solutions for their economic woes.

Obama's aides said privately that they felt they had a good shot at a win in Texas, but were less certain about Ohio, where they braced for a possible loss.

Obama has spent the past couple of days fending off attacks by Clinton.

"What precise foreign-policy experience is she claiming that makes her qualified to answer that telephone call at 3 am in the morning? Obama asked of the former first lady at a town-hall meeting in Westerville, Ohio. It was a reference to dueling television ads over who would exercise superior judgment in responding to a national emergency in the middle of the night.