Scott and other Republican leaders spent more than two years fighting the Affordable Care Act, which Obama and congressional Democrats approved in March 2010. That fight included a Florida-led legal challenge that ended up in a landmark U.S. Supreme Court case. Justices upheld most of the law, but said states must be able to decide whether to carry out the law's Medicaid expansion.

Republicans have rejected another part of the law that gave the state the choice of running a health-insurance exchange. They decided to let Washington run the exchange, which will be an online marketplace where Floridians can shop for insurance coverage.

But in explaining his decision on the Medicaid expansion, Scott said the overall Supreme Court ruling and Obama's re-election in November cemented the Affordable Care Act as the "law of the land." He said he has not changed his view that the best way for people to get health coverage is through their jobs, but he said his decision is aimed at making sure all Floridians have access to care.

"It is not a white flag of surrender to government-run health care,'' said Scott, who made a fortune as the hard-driving chief executive of a hospital company.

Perhaps the most-important part of the expansion is that it would make Medicaid coverage available to hundreds of thousands of childless adults who in most cases are not currently eligible for the program. Also, the law would raise the income threshold for eligibility to 138 percent of the federal poverty level, which is higher than the threshold for many people currently enrolled.

The federal government has promised to pay 100 percent of the expansion costs from 2014 through 2016 and then gradually reduce that share to 90 percent in 2020. But Scott and many Republican lawmakers have repeatedly raised questions about how much money the state could be required to pay in the future.

A report released last month by the state Agency for Health Care Administration indicated that Florida could face costs of $3 billion or more over 10 years. But analysts are scheduled to meet March 1 to revise the estimates, and the new numbers could play an important role as lawmakers decide whether they want to pursue an expansion.

While Scott would require what is known as a "sunset" process after three years, it was not immediately clear Wednesday what would happen if the expansion was not reauthorized. Such a process raises the possibility of newly eligible people losing their benefits after three years.

House Democratic Leader Perry Thurston, D-Plantation, said he would prefer that Scott didn't seek the three year-restriction on the expansion. Nevertheless, Thurston said he was pleased by Scott's announcement.

"I am confident that this important and necessary expansion of Florida's Medicaid program will improve the quality of health care in our state and can be achieved in an affordable manner,'' Thurston said.

But with Scott running for re-election in 2014, he could face a backlash from conservatives who put him into the governor's mansion.

"Will Medicaid expansion cover me for the knife (Scott) just buried in my back?'' Henry Kelley, a tea party leader in Florida, said in a Twitter message.