President Obama won the White House in large part because voters, as he would put it, chose hope over fear. Change was at the core of his appeal.

Now, Obama needs to make that sale all over again if he is to succeed in pushing through an overhaul of the health-care system - the sternest political test so far in his young presidency.

Recent polling shows fear rivaling hope, with Americans divided over some of the difficult choices in the developing overhaul package. Voters express worry that government might assume too much control of health care, and most pronounce themselves satisfied with the insurance they have. On the other hand, their dissatisfaction with the costs and complexity of the current system is through the roof, and huge majorities say change is needed.

"People really need to know how they will pay less, how the plan will be paid for, and how they will have choice," Democratic pollster Stanley Greenberg wrote in a memo summarizing the results of his recent Democracy Corps survey on the issue. "Their presumption is that reform costs more, not less - and so, we have to be doubly diligent, respecting how personal a choice this is for people in very tough times."

Of 1,013 people, all of them 2008 voters, whom Greenberg's firm surveyed two weeks ago, 57 percent said they were dissatisfied with the health-care system overall, but only a plurality supported what they had heard about Obama's plan; two-thirds of Republicans and 49 percent of independents opposed it, and senior citizens were more likely to oppose it than those under 65.

The biggest obstacle to building majority support for for Obama's plan, Greenberg said, is the finding that 75 percent of respondents were satisfied with their own health coverage. That makes people averse to risk, he said.

Greenberg was the pollster for the Clinton White House in 1993 when its push for health-care changes drew a similar mix of support and skepticism. That effort collapsed in the face of strong opposition and effective lobbying by the special interests involved - as well as missteps by the Clintons.

This time, Obama is headlining the lobbying effort himself, using a variety of forums and media platforms as he did during his presidential campaign and to win passage in February of the $787 billion stimulus package.

Obama kicked off the health-care salesmanship last week with a town-hall meeting in Wisconsin, and followed it Monday in Chicago with a big speech to the American Medical Association in which he laid out his fullest case yet for reform. Obama called the health-care delivery system, with its ever-increasing costs, an unacceptable drag on the economy that leaves 46 million people uninsured.

Yesterday, Obama's political organization sent email pushing reform to millions of addresses gathered in the 2008 campaign, and ABC News plans to host four news programs centered on health care next Wednesday at various White House locales.

The president argues that this year's effort will be unlike 1993's, citing last week's Senate passage of legislation allowing the Food and Drug Administration to regulate the tobacco industry. Obama also recently gathered health-industry leaders at the White House, where they pledged to trim $2 trillion in the cost of care to help pay for reform.

"What makes this moment different is that this time - for the first time - key stakeholders are aligning not against but in favor of reform," Obama said in Chicago. "They are coming together out of a recognition that while reform will take everyone in our health-care community doing their part, ultimately, everyone will benefit."

A key element of Obama's proposal is a public insurance plan that would reduce the cost of health care by competing with private-sector insurance plans and drawing in more uninsured Americans, increasing the risk pool.

The prospect of a government-run plan - though White House senior adviser David Axelrod said yesterday that Obama was not wedded to a public plan's being entirely funded or run by the government - has sparked intense opposition, with congressional Republicans seeking to tie the idea to the costly bailouts for financial institutions and the auto industry.

The health-care system represents 20 percent of the U.S. economy, with tons of moving parts and a string of special interests who could mobilize as more specifics emerge from Congress.

That very complexity presents practical hurdles to getting meaningful change done.

Congressional budget officials are estimating the cost of the overhaul at beyond $1 trillion over 10 years, sparking concern among lawmakers that could spill over into the public. Democrats who control both Houses are divided on how to pay for the package - some moderate senators, for instance, want to tax private health benefits, while most in the House leadership do not.

As Obama moves forward with the sales effort, he will have to turn around public skepticism to keep the pressure on Congress. A Rasmussen Reports poll released Monday found that only 32 percent of Americans believed a government-run insurance plan would, in fact, lower costs.

Contact staff writer Thomas Fitzgerald at 215-854-2718 or tfitzgerald@phillynews.com.