Two-thirds of the country could opt out of the public option, based on a Real Clear Politics analysis.

Senate Majority Leader Harry Reid (D-Nev.) is promoting a federal government-run insurance option that states would be able choose whether or not to participate in. But if the decision falls to the state legislatures and governors, as indications are it would, the vast majority of states could choose to opt out.

Ten states are completely controlled by Republicans (including the state House, Senate and governor's mansion). Meanwhile, Republicans have control of at least one chamber of the state legislature or the governor's mansion in 23 states.

Potentially, any state with at least partial Republican control could choose to opt out of the public option. That would leave 33 states, totaling 200 million people, that would not be included in the most decisive, and divisive, portion of health care reform.

If only states totally controlled by Republicans were to opt out, 70 million people would be without a public option.

In Virginia, Democrats currently control the state Senate and governor's mansion, but Republican Bob McDonnell leads by more than 10 points with one week to go in the gubernatorial election. Should he become governor and the option be available, McDonnell would opt out.

"Bob McDonnell does not support nationalized heath care," said McDonnell spokesman Tucker Martin. "As a result, he does not support Virginia's participation in a federal public health insurance system. As governor he would opt Virginia out of such a system."

Whether or not Reid's proposal ever goes up for a vote on the Senate floor remains in flux, however. Sen. Joe Lieberman (ID-Conn.) said today he was against the public option, even with an opt-out clause, and would join Republicans in withholding it from a floor vote.

Should Reid's plan make it through both chambers of Congress, the public option would likely remain in at least 17 states where Democrats have complete control and 97 million people reside.

Washington D.C. was not included in RCP's analysis. Population data was taken from the U.S. Census Bureau's 2008 population estimates.