WASHINGTON (November 19, 2009)—The U.S. Senate health care bill would make a government health plan widely available, the Congressional Budget Office said Thursday.

The CBO said about two-thirds of the U.S. population would have a public plan available in their state, even though the Democrats' 10-year, $848-billion bill would allow states to opt out.

Wide availability doesn't mean the government plan would dominate the market, however.

The CBO estimates only 3 million to 4 million people would sign up, partly because private insurance plans would be able to offer lower premiums.

While most Americans would be able to observe the new experiment with government coverage, few would actually participate.