DENVER | After taking a beating at the hands of Missouri voters in August, "Obamacare" could be roughed up once again at the ballot box in November.

Following the lead of the successful Missouri initiative, which passed with 71 percent of the vote, Arizonans, Coloradans and Oklahomans will decide this fall whether to approve proposed constitutional amendments that would allow them to opt out of key provisions of President Obama's signature national health care law.

The three initiatives prohibit the government from forcing individuals to buy health care insurance - a "mandate" that critics say violates the U.S. Constitution - and would allow patients and employers to pay providers directly without penalty. The idea is to protect state residents from "the ongoing takeover of health care by government," backers of the Colorado campaign say...