WASHINGTON » Threatened with repeal just weeks ago, President Barack Obama’s health care law now appears on track in close to half the states, with others playing catch-up and the administration readying a fallback for states not wishing to participate.

Friday was the original deadline for states to notify Washington whether they would play a role in building new health insurance markets through which the uninsured can get coverage starting in 2014. Though the administration granted a month’s extension, most states have already made their intentions known.

As of Friday, 23 states, including Hawaii, plus Washington, D.C., were proceeding; 15 said they would defer to the federal government to run their markets; and 12 were still mulling over their options. The mostly blue group proceeding included five Republican-led states. The undecided included several states that seemed to be moving toward an active role.

Republican presidential candidate Mitt Romney had vowed to begin dismantling "Obama­care" his first day in office. But Romney lost, and instead GOP governors are scrambling to see whether they can find an accommodation with the administration after two years of fighting Obama’s signature law.

"The president won the election … and New Jersey is going to comply with the Affordable Care Act," Republican Gov. Chris Christie said Friday. Christie said he still has questions about costs and is weighing his decision. Earlier this year he vetoed legislation creating a state exchange, as the new insurance markets are called.

A check by The Associated Press found that 16 states plus Washington, D.C., want to build their own exchanges. Starting Jan. 1, 2014, individuals, families and small businesses will be able to buy private coverage through an exchange in their state, with most consumers getting government assistance to pay premiums. The exchanges will also help steer low-income, uninsured people into expanded Medicaid programs in many states.

Another seven states have indicated they want to partner with Washington to build their exchanges. Ohio joined this group Friday, and West Virginia officials said they’re heading in the same direction.

Fifteen mostly Republican-led states say they’ll defer to the federal government to build and run their markets. Georgia and Wisconsin formally joined that group Friday. However, New Hampshire, where Demo­crats won control of the state House in the election, is taking a second look at its decision to default to the feds.

Finally, another 12 undecided states now have until Dec. 14 to determine what role, if any, they’ll play.