Florida Gov. Rick Scott endorsed the Medicaid expansion in President Obama’s healthcare law on Wednesday, delivering a political coup to the White House.

Scott isn’t the first high-profile GOP governor to accept the Medicaid expansion, but he’s arguably the biggest get for the Obama administration. Florida led the 26-state lawsuit that said the entire healthcare law — specifically including its Medicaid expansion — was unconstitutional.

Roughly 1 million Floridians will have access to healthcare coverage if the state legislature approves Scott’s plan. He said he would only support the expansion for three years, and would back out if the federal government backs away from its funding commitments.

“While the federal government is committed to paying 100 percent of the cost of new people in Medicaid, I cannot, in good conscience, deny the uninsured access to care,” Scott said at a news conference.

Scott said last year that he would not participate in the expansion, and he has also refused any role for the state government setting up an insurance exchange — the other half of the healthcare law’s coverage expansion.

“This would be devastating … this is an expansion that just doesn’t make any sense,” Scott said in a 2012 interview with Fox News.

{mosads}But Scott is also facing a deep slide in the polls as he approaches what’s sure to be a hard-fought reelection campaign. And his decision comes the same day the Obama administration approved a Medicaid waiver Scott had requested, which will allow him to expand the use of managed care within the program.

Scott sought to reassure conservatives on Wednesday that he still opposes “ObamaCare” by emphasizing his refusal to implement an exchange.

“Expanding access to Medicaid services for three years is a compassionate, common-sense step forward … it is not a white flag of surrender to government-run healthcare,” Scott said.

He said he still opposes the federal overhaul, but accepted that the Supreme Court’s decision and Obama’s reelection ensured that the Affordable Care Act is the law of the land.

“I believe in a different approach. But it doesn’t matter what I believe. It doesn’t matter what anybody believes. The Supreme Court made their decision,” he said.

The Supreme Court’s healthcare decision made the Medicaid expansion optional for states. The federal government initially covers 100 percent of the cost of the expansion, dropping to 90 percent in a few years.

Florida argued before the Supreme Court that the expansion was coercive — too good of a deal for states to practically refuse. And even though the court made it easier to opt out, Scott’s decision Wednesday seemed to indicate that the expansion is indeed an attractive proposition for states.

Scott is the seventh GOP governor to accept the Medicaid expansion. Other high-profile members of that group include Arizona’s Jan Brewer, Ohio’s John Kasich and Michigan’s Rick Snyder.

Scott said Florida should only agree to the expansion for three years — until federal funding drops to 90 percent. Although it’s politically difficult to take away benefits once they’ve been provided, Scott said Florida should reassess the expansion and use the next three years to identify new ways of improving its healthcare system.

He also said Florida would back out if the federal government doesn’t follow through on its commitment to initially fund the entire expansion — a key concern for some governors, especially given Washington’s budget-slashing climate.

But the White House has sought to reassure governors the funding will be there, even backing away from unrelated Medicaid cuts it previously supported.

This story was last updated at 6:02 p.m.