New Jersey Gov. Chris Christie isn’t letting his state implement one of the biggest pieces of President Barack Obama’s health care plan — at least not yet.

On Thursday, Christie, who’s in the national spotlight again as a potential running mate for Mitt Romney, vetoed the Legislature’s bill that would have set up a health insurance exchange in the state. He called it the safe move, since the Supreme Court isn’t expected to rule on the Affordable Care Act until the end of June.

“Because it is not known whether the Affordable Care Act will remain, in whole or in part, it would be imprudent for New Jersey to create an exchange at this moment in time before critical threshold issues are decided with finality by the court,” Christie said in a statement.

Despite the veto, the state has received almost $9 million to study and plan for an exchange, an insurance marketplace that would let individuals and small businesses shop and compare health plans. A central part of the federal health reform law, the state health exchanges — which will launch in 2014 — will enable low- and middle-income individuals to receive government subsidies to help them purchase coverage.

Christie’s veto signifies the tough spot Republican governors are in — they don’t like the health reform law, but if their states don’t set up exchanges, the Obama administration says the feds will set one up by 2014, when the law’s fuller coverage expansions go into effect.

As recently as last week, Christie said publicly he wasn’t sure how he will decide on the Legislature’s exchange bill. That sparked a flurry of activity from local and national groups pushing Christie to block the bill.

“We’re thrilled with the governor’s unconditional veto,” said Steve Lonegan, New Jersey state director of Americans for Prosperity. “We believe he listened to the message not only in New Jersey but from around the country. This sends a powerful message to governors across the country that they should all be vetoing exchanges.”

Jeff Brown of New Jersey Citizen Action said consumer groups were “clearly disappointed” with Christie’s decision. The governor’s past statements about waiting on a Supreme Court decision made it virtually impossible that he would have approved the exchange bill, but consumer advocates had been hoping for a “conditional veto” — a maneuver that would have potentially let the Legislature come back to the bill after a Supreme Court decision.

“I think this is national politics intruding on something that could potentially be good for New Jersey,” Brown said, pointing out that 1.3 million of the state’s residents lack health insurance coverage.

Christie isn’t the only GOP governor who’s had to dance carefully around the exchange issue in the face of the national spotlight. Gov. Bob McDonnell of Virginia, also considered a possible pick for vice president, has stated his preference for a state-based exchange but only if the Supreme Court upholds health reform.

The veto makes Christie the second Republican governor to reject an exchange bill. New Mexico Gov. Susana Martinez issued a veto in April 2011, arguing that the state didn’t have enough information from the feds about how the exchanges would operate.