Paul Ryan Promises Republicans Will Complete 'Obamacare' Replacement Bill This Year

The House speaker said the GOP will defund parts of the ACA immediately.

A replacement plan will be written to allow new programs to be phased in later, Ryan said.

His leadership team has yet to introduce any legislation, let alone a bill that has the support of a majority of representatives. Still, he said he was confident a bill could be composed and approved swiftly.

However, hospitals, doctors and even some in the GOP's ranks have urged caution, saying it would be unwise to defund or repeal the law without a clear replacement plan.

"If they don't," he said, "'Obamacare' continues to unravel." He added that the insurance marketplaces could collapse.

"Now they're going to own it, and all the problems in the health care system — and there have been many throughout the years, no one has solved all of them — are going to be on their back."