"What we shouldn't be doing is tearing each other down," Obama said. "We should be lifting the country up."
It was an unusually pointed exchange in an otherwise civil debate that largely plowed familiar ground in the long slog toward the Democratic nomination, ahead of March 4 primaries in Texas and Ohio that are seen as must-wins for Clinton if she is to catch the surging Obama.
The debate at the University of Texas in Austin, broadcast live on CNN and later in Spanish on Univision, seemed unlikely to shake up the race between the two candidates, though it illuminated some differences.
The two sparred over the nuances of their plans for health-care coverage, a paramount issue among Democratic voters, and about the proper approach toward Cuba in the wake of dictator Fidel Castro's resignation after nearly 50 years in power.
Clinton came into the debate with her longtime front-runner status having evaporated after 11 straight defeats to Obama, the latest being the Democrats Abroad result announced yesterday.
Texas and Ohio, with their sizable delegate allotments, loom as potential last stands for Clinton, even supporters acknowledge, as she tries to halt Obama's growing lead in pledged delegates.
Advisers hope Clinton can do well enough in those two states, along with Pennsylvania on April 22, to deny Obama the 2,025 delegates needed to win the Democratic nomination, and to throw the decision to the party leaders and elected officials who will serve as superdelegates to the national convention in Denver in August.
Clinton's 17-point loss in Wisconsin on Tuesday was especially devastating for her, because Obama captured demographic groups, including blue-collar workers, that had been key to her earlier victories.
