PHOENIX - A proposal by Democrats to create a government-run health-care plan to compete with private insurers will be too expensive and would make the government a "Big Foot" in the insurance market, Sen. John McCain said Wednesday.

The Arizona Republican told more than 100 medical professionals in a town hall-style meeting at Phoenix Children's Hospital that the so-called public option would be "artificially less expensive" than the private plans and result in a migration to the government plan.

"I believe that a government plan would be a Big Foot in the market," he said.

President Obama and most Democrats say the choice of a public plan would serve to balance the power of private insurers. But insurance companies see it as a step toward a government takeover, and many business groups agree. Polls indicate public support for a government option.

McCain said he fears a government option would provide an advantage over private insurers and that funding such a program isn't feasible.

The Congressional Budget Office estimates that the plan would cost the government $1 trillion over the next decade and cover one-third of the nation's uninsured, or 16 million people.

"If you do the math," McCain said, "it only covers one-third of the uninsured. You want to insure everyone, so that's a $3 trillion bill. I don't know where that money comes from."

Lawmakers will further debate the issue when they return from a one-week recess on Monday. They will have four major options to consider on a government plan.

The plan from the Senate Health, Education, Labor and Pensions Committee calls for a nationwide plan to be run by the federal government. An upfront loan from taxpayers would get the plan started, but it would have to pay its own way after a few months, relying on premiums collected from beneficiaries to stay solvent.

One favored by Republicans would have no public plan, maintaining the current system in which the government covers the elderly and low-income people, but most workers and their families get job-based insurance.