SAN DIEGO — Democratic Sen. Hillary Rodham Clinton said Friday she's the last remaining presidential candidate who is advocating universal health care coverage.

"I think that's one of the most important differences separating Democrats from Republicans," Clinton told a noisy rally of some 7,000 backers at San Diego State University. "When we stand on that stage against whoever the Republicans nominate, it's important that we stand there 100 percent committed to universal health care as soon as we can possibly achieve it."

Clinton favours mandatory universal coverage, tax credits for working families to make insurance more affordable and requiring businesses to offer insurance to employees or pay into a pool for people without it. Rival Barack Obama calls for mandatory coverage for children, but no mandate for all.

He aims for universal coverage by requiring employers to share costs of insuring workers and by offering coverage similar to that in plan for federal employees.

The two Democratic candidates sparred over the issue at Thursday night's debate.

Clinton spent Friday morning conducting satellite interviews with local television stations scattered throughout the 22 states holding Democratic primaries and caucuses on Super Tuesday.

Most polls have shown Clinton with a lead in California, the biggest prize of all and she was seeking to seal the deal with her campaign swing. After San Diego, she was heading to a rally in San Jose and was raising money in San Francisco. She argued that with the departure of John Edwards from the race, she is the only remaining candidate — Democrat or Republican — who is calling for universal coverage.

"That's why I put forward a plan to cover everyone," said Clinton. She argued in the debate and at the rally that Obama's plan would leave millions without coverage.

"We got into a back and forth about it in the debate last night, but you see if we don't move for universal coverage, we'll still have people falling through the cracks."

She said her plan also calls for preventive efforts and healthy lifestyle measures that can only be effective if everyone is covered.

"That's only possible if everybody is included," said Clinton. "Who would we decide to leave out?"

Clinton first confronted the issue as first lady when she headed a failed effort to overhaul the nation's health care system, and she said her long experience makes her best prepared to deal with an issue that is getting more and more critical.

Clinton argued that whichever candidate voters choose will make history as either the first woman or the first black to get the party's nomination, and she offered her own self-serving prediction.

"Isn't it thrilling to know that one of the people on that stage last night will make history as our 2008 Democratic nominee," said Clinton. "If we work together, you are looking at the next president of the United States. This has been an incredible campaign."

She sought to cast a sense of history.

"We cannot just think about the next election, we have to think about the next generation," said Clinton.