Missourians expected to reject key health reform provision on Tuesday

"The good thing about Prop C is because it's the first in the nation vote on Obamacare, that it will be a wake-up call to other state lawmakers that this will be both good policy and good politics," she said.

"These will be very helpful for states in giving them the ultimate back-up plan against an unconstitutional individual mandate ... If Missouri passes this, and if the current lawsuits are thrown out of court, it can allow Missouri to launch a future, solely 10th Amendment [state's rights] challenge against the mandate. And finally, it can empower the attorney general to take up the case on behalf of individuals starting in 2014 when the mandate goes into effect."

A St. Louis Post-Dispatch / KMOV-TV poll last month of 300 probable Democratic and 300 probable Republican voters found stronger feelings on the side of the GOP. While 67 percent of Republicans said they'd vote 'yes' (16 percent said they'd vote 'no' and 17 percent were undecided), only 48 percent of Democrats said they'd vote 'no' (27 percent said 'yes' and 25 percent were undecided).

Opponents of the measure say turn-out is expected to be low and add that there's been little campaigning except by the GOP's base. The Missouri Hospital Association, which stands to gain if more patients are covered by insurance plans, has been the single largest contributor to the 'no' campaign, according to ALEC.

The Missouri referendum would amend state law to “deny the government authority to penalize citizens for refusing to purchase private insurance or infringe upon the right to offer or accept direct payment for lawful health care services.” 

Five other states — Arizona, Georgia, Idaho, Louisiana, and Virginia — have already enacted such legislation. The governors of Florida and Oklahoma have vetoed similar legislation.

In addition, two states — Arizona and Oklahoma — have similar constitutional amendments on their November ballots. Last week, a Florida circuit court judge knocked a similar constitutional amendment off the ballot, calling its wording "manifestly misleading" because its summary language appears to guarantee that patients would never again have to wait in a doctor's office if it passes.