Arizona's state legislature approved ObamaCare's Medicaid expansion in two closely watched votes on Thursday, handing a victory to Republican Gov. Jan Brewer and a defeat to conservative lawmakers.
The policy will take effect next year and extend healthcare coverage to 300,000 low-income patients in Arizona.
The Affordable Care Act encourages states to expand their Medicaid programs up to 133 percent of the federal poverty level using mostly federal dollars.
"With the landmark votes in the House and Senate, legislators have tackled the issue that is Job One every session — adoption of a responsible state budget — and enacted Arizona's most sweeping healthcare legislation in decades," Brewer said in a statement after the votes.
"It will extend cost-effective care to Arizona's working poor using the very tax dollars our citizens already pay to the federal government."
The Medicaid expansion is a core component of the Affordable Care Act, and many Republican governors have refused to pursue it as a way to thwart the law.
Conservatives also argue that longer Medicaid rolls will sink state budgets, especially as healthcare costs rise.
Brewer's support for the expansion came as a surprise to people familiar with her strong opposition to ObamaCare.
The governor, in office since 2009, has also been a vocal critic of President Obama on immigration issues, leading to a heated confrontation between the two on a Phoenix tarmac in 2012.
In a January speech, she vowed to create "circuit breaks" to protect Arizona's budget from onerous Medicaid bills.
"I won't allow 'ObamaCare' to become a bait and switch," she said to applause from Republicans.
Twenty-three states, mostly led by Democrats, are pursuing the expansion. Twelve are still deciding, and 15 have refused the option outright.