Updated

A public health insurance option, which Republicans strongly oppose, should be included in any plan to keep the insurance companies honest and prices down, President Obama said Thursday at a town hall gathering in a Green Bay, Wis., high school.

As part of his latest effort to push for aggressive action this year, Obama said Americans who can't afford health insurance need to be provided with more affordable options -- provided by the government if not private insurers.

"This is both a moral imperative and an economic imperative, because we know that when someone without health insurance is forced to get treatment at the ER, all of us end up paying for it," he said.

Obama said his administration is working to establish a so-called "Health Insurance Exchange,"  which would act as a one-stop shop for a health care plan and allow consumers to compare benefits and prices and choose their preferred plan. It would ensure none of the plans deny coverage on the basis of pre-existing conditions.

Obama said he wants to ensure an option exists for people "where the free market fails. And we have to admit that the free market has not worked perfectly when it comes to health care."

But, he said, he is not interested in a system of nationalized health care though a single-payer system does have some appeal.

Answering a question at the town hall meeting, the president said the government is not going to force any change upon people who are pleased with the plan they already have with their employer. He did not indicate what the government would force on people who are displeased or have no insurance.

Obama said talk of socialized medicine in America is incorrect. He told his audience, "So when you hear people talking about that, understand, I don't know anybody in Washington that's proposing that, certainly not me."

Obama has run into opposition from fellow Democrats in Congress and the nation's largest doctors' association, the American Medical Association.

Dismissing criticism, Obama did not directly respond to AMA President Nancy H. Nielsen, who said she remains unconvinced of the wisdom of the White House's call for a public health plan. Instead, Obama broadly described his critics as naysayers.

"I know there are some who believe that reform is too expensive, but I can assure you that doing nothing will cost us far more in the coming years," Obama said. "Our deficits will be higher. Our premiums will go up. Our wages will be lower, our jobs will be fewer, and our businesses will suffer."

The president's warnings come as reservations have been expressed by health care providers, Congress and the public. During the brief ride from the airport to the town hall-style meeting, Obama passed several hundred protesters. Many held signs such as "NObama" and "No to Socialism."

White House aides brushed off the protests and instead focused on the president's message of the day: Inaction on health care overhaul is too dangerous to put off and would cost money the country simply doesn't have.

"I will not welcome endless delay or a denial that reform needs to happen," the president said in a speech that contained no new policy proposals but instead repeated oft-repeated generalities.

Obama's visit to Green Bay was designed to put some momentum behind his push for congressional action this year on overhauling a health care system he says is too expensive and complex. He said he's open-minded and "happy to steal other people's ideas."

Obama has set an August deadline for an overhaul that has vexed Washington for decades.

As he took questions at the town hall meeting, Obama acknowledged GOP opposition to a public health plan.

"It's not clear that it's based on any evidence as much as it is their thinking, their fear that once you have a public plan that the government will take over the entire health care system," he said. "That's going to be a significant debate."

The Associated Press contributed to this report.