Updated

The Supreme Court guessing game is over, but the drama may just have begun.

The court's Thursday ruling upholding most of President Obama's health care law, sparked a frenzy of reaction from political figures, business leaders, medical professionals and ordinary Americans. By Friday, with the dust starting to settle, the debate is sure to intensify over the political, economic and medical ramifications of a landmark 5-4 decision that will affect the lives of virtually every American.

The ruling is a victory for the president, ensuring for now that his signature domestic policy achievement remains mostly intact. It also ensures that the law will play a prominent role in the general election campaign, as Republican candidate Mitt Romney vows to repeal the law if elected.

The so-called individual mandate, requiring that all Americans have health insurance, takes effect in 2014, at the same time that the law would prohibit insurance companies from denying coverage to people with existing health problems. Most experts had said the coverage guarantee would balloon costs unless virtually all people joined the insurance pool.

Most Americans already are insured. The law provides subsidies to help uninsured middle-class households pay premiums and expands federal health care for poor people.

More On This...

"Whatever the politics, today's decision was a victory for people all over this country," Obama said, speaking on national television from the White House.

"It should be pretty clear by now that I didn't do this because it was good politics," he said. "I did it because it was good for the country."

Romney pinned the court's decision to the election and asking voters to render their own ruling.

"If we want to get rid of ObamaCare," he said, "we're going to have replace President Obama."

Democrats, many of whom were bracing for the court striking down the mandate for individuals to buy health insurance, celebrated the decision Thursday. Rep. Charlie Rangel, D-N.Y., told Fox News that the ruling "gives us the opportunity to re-sell the bill, which we did not do before."

But Republicans vowed to re-double their campaign to repeal the still-controversial law.

The ruling "underscores the urgency of repealing this harmful law in its entirety," House Speaker John Boehner said in a written statement. "Republicans stand ready to work with a president who will listen to the people and will not repeat the mistakes that gave our country ObamaCare."

Chief Justice John Roberts, who was appointed during a Republican administration, joined the four left-leaning justices on the bench in crafting the majority decision.

The ruling relied on a technical explanation of how the individual mandate could be categorized. Roberts, in the opinion, said the mandate could not be upheld under the Constitution's Commerce Clause. However, it could be upheld under the government's power to tax.

"The Affordable Care Act is constitutional in part and unconstitutional in part  The individual mandate cannot be upheld as an exercise of Congress's power under the Commerce Clause," Roberts wrote. "That Clause authorizes Congress to regulate interstate commerce, not to order individuals to engage it. In this case, however, it is reasonable to construe what Congress has done as increasing taxes on those who have a certain amount of income, but choose to go without health insurance. Such legislation is within Congress's power to tax."

Roberts stressed that the decision does not speak to the merits of the law. "We do not consider whether the act embodies sound policies. That judgment is entrusted to the nation's elected leaders," he said.

The ruling did rein in one element of the law -- the expansion of Medicaid across the country to take in millions of low-income Americans. The opinion allows Washington to offer more funding to states to expand the program, but says the federal government cannot penalize states for not participating in the new program by withholding existing Medicaid funds.

Justice Anthony Kennedy, who was thought to be the swing vote on the decision, joined the minority in describing the whole law as invalid.

"The act is invalid in its entirety," Kennedy said from the bench. He went on to say the administration went to "great lengths to structure the mandate as a penalty, not a tax" -- challenging the majority's rationale for upholding the mandate.

Despite the persistent resistance to the law and the possibility that it could still be repealed, the historic decision Thursday will offer some measure of vindication for Obama, who devoted the first half of his term to pushing it through Congress.

The overhaul was one of the central planks of Obama's 2008 run for president. The faltering economy only later took a leading role in the race as the financial markets spiraled around the time of the party conventions. Obama, after taking the oath of office, dispatched with his administration's recession response by swiftly passing through the roughly $800 billion stimulus package.

The president immediately pivoted back to health care. He tasked allies in Congress with working out the specifics of a proposal, a process that would play out on the national stage over the course of a year, until its passage with a series of deals by Democrats, who went on to sustain losses in the 2010 midterm elections.

The decision Thursday virtually guarantees the health care law will remain at the forefront of the 2012 campaign.

The Associated Press contributed to this report.