Democrat Barack Obama, seeking to distance from his leading rivals, touted his health care expansion package as doing more to cut costs and deal with root problems facing consumers "than any other proposal in this race."

Obama's two main rivals the Democratic presidential nomination — New York senator Hillary Rodham Clinton and former North Carolina Sen. John Edwards — have offered universal health care plans, while his stops short of mandating everyone have health insurance. Obama routinely describes his rivals' plans as similar in thrust, but he began sharpening those differences as he opened his latest campaign swing Saturday.

"Cost is the number one reason that 47 million Americans do not have health insurance and thousands more are edging toward bankruptcy every day," Obama told a town hall-style meeting of about 350 people at a Council Bluffs high school. "That is wrong, and it's why my plan does more to cut the cost of health insurance than any other proposal in this race."

Obama sought to distance requirements in his rivals' plans that consumers to buy health insurance, saying that thinking is misplaced.

"What I have said repeatedly is that the reason people don't have health insurance is not because they don't want it, it's because they can't afford it," said Obama.

While Obama conceded plans for the leading rivals are similar, he said the insurance mandate is a key difference.

"It's unfortunate that Senator Obama didn't have the courage to produce a universal health care plan and instead wrote a plan that leaves 15 million Americans without coverage," Clinton spokesman Mo Elleithee said. "That is unacceptable."

Edwards spokesman Dan Leistikow also noted that Obama's plan would leave millions uninsured.

"Without primary or preventive care, they would continue to rely on the emergency room, driving up premiums for everyone," he said. "Senator Edwards' plan covers every man, woman and child in America, and cuts the costs for families and businesses."

While rival Clinton has built a substantial lead in national surveys of the Democratic field, the race in Iowa between Obama, Clinton and Edwards is extremely tight heading into the state's leadoff precinct caucuses, the traditional opening test of the presidential nominating season.

The stakes are very high for Obama and Edwards because Clinton has forged a significant lead in most of the early voting states, and a win in Iowa would give her momentum that would be difficult to derail. Faced with that, Obama has been sharpening his differences with Clinton.

The Illinois senator drew a distinction with Clinton on how he would go about pushing a universal health care plan. He routinely gives the New York senator credit for trying to overhaul health care as first lady, but says it failed largely because she was too secretive.

"What I am convinced of is if we actually hope to pass universal health care this time around we have to bring Republicans and Democrats together," said Obama. "We have to have an open and transparent process so that the American people participate in the debate and see exactly what we're doing."

Obama and Clinton opened their campaign day Saturday with events in the heavily Republican western portion of the state, Obama in Council Bluffs and Clinton in Sioux City. Both were swinging through a long list of small-town stops, and Obama argued that time is getting short for activists who are notoriously slow in making up their minds to reach a decision.

"It's getting nippy, it's starting to get close and some of you are starting to make up your mind," said Obama.