Washington (CNN) -- The U.S. Supreme Court's narrow upholding of the health care reform law now launches a complex political ballet, with President Barack Obama and Democrats claiming victory and Republicans immediately seizing on the word "tax," vowing to repeal the law "lock, stock and barrel."
In a 5-4 decision, the court upheld the law and found that the so-called individual mandate is constitutional under Congress' taxing power but not under the commerce clause of the Constitution, as the government originally had argued.
Republicans -- including presidential candidate Mitt Romney -- claimed the mandate should be seen as a tax increase. Obama had previously rejected the idea that the mandate amounts to a tax.
Romney lashed out at the ruling and the president, claiming the law's provisions to impose a penalty on those who aren't insured amounts to a tax increase. Other parts of the law require individuals making more than $200,000 to pay more into Medicare and imposes an excise tax on high-cost employer health insurance plans if their plan cost tops $10,200 for individual coverage and $27,500 for family coverage.
"Obamacare raises taxes on the American people by approximately $500 billion," Romney said Thursday.
Chief Justice John Roberts clarified the tax issue in his opinion: "The Federal Government does not have the power to order people to buy health insurance. (It) would therefore be unconstitutional if read as a command. The Federal Government does have the power to impose a tax on those without health insurance. (It) is therefore constitutional, because it can reasonably be read as a tax."
Other Republicans also latched onto the tax increase refrain.
"Here's the bottom line now," said Sen. Marco Rubio, R-Fla. "It is constitutional according to the Supreme Court because it is a tax increase ... now millions of Americans will have an IRS problem beginning in 2014."
Republicans likely will use the tax argument as a battle cry on the campaign trail as Romney quickly repeated his vow to repeal the law if he is elected president.
"What the court did not do on its last day of session, I will do on my first day if I am elected president of the United States," Romney said Thursday. "I will act to repeal Obamacare."
For his part, Obama sees his role in the protracted saga as that of a leader willing to take a politically unpopular stand on health care.
"I didn't do this because it's good politics. I did it because I believed it was good for the country. I did it because I believed it was good for the American people," Obama said.
Later Thursday, in a memo from Democratic officials, the Obama re-election campaign added: "All three branches of government have now agreed that President Obama's health care law is the right thing to do...It's time to move past the same political battles and fully implement the law."
Both sides will now take their case to the American electorate heading into the fall election.
Republicans frustrated, Democrats elated
On Capitol Hill, Republicans who fought hard against the law's initial passage were not happy.
"The president of the United States himself, promised up and down that this bill was not a tax," Senate Minority Leader Mitch McConnell said from the Senate floor. "This is one of the Democrats' top selling points because they knew it would not pass if it was a tax. Well, the Supreme Court has spoken -- this law is a tax. The bill was sold to the American people on a deception."
House Speaker John Boehner, R-Ohio, was more blunt. "The government could decide that we are going to tax you if you don't eat broccoli on Tuesday," Boehner said. "Apparently now that is constitutional, but I don't think it is a very wise law."
House Majority Leader Eric Cantor, R-Virginia said he was "disappointed" in the decision and on his way into a closed door House GOP meeting on the ruling. He said the House will vote after it returns from July Fourth recess to repeal the health care law.
Meanwhile, Democrats in Congress were elated.
A visibly relieved Senate Majority Leader Harry Reid, D-Nevada, applauded the decision from the Senate floor. Like Obama, the veteran lawmaker spent enormous political capital marshaling his caucus and pushing the law's passage.
"Passing the Affordable Care Act was the greatest single step in generations toward ensuring access to affordable, quality health care for every person in America regardless of where they live, how much they make," Reid said Thursday.
The key House leader who pushed through the bill in 2010 indicated the court's ruling was a vindication of months of work.
"In passing health reform, we made history for our nation and progress for the American people. We completed the unfinished business of our society and strengthened the character of our country," said House Minority Leader Nancy Pelosi, D-California, who was House speaker until her party lost the majority in the 2010 midterm elections.
"We ensured health care would be a right for all, not a privilege for the few. Today, the Supreme Court affirmed our progress and protected that right, securing a future of health and economic security for the middle class and for every American."
And the ruling was a much-needed win for a president locked in a tough re-election campaign.
"It is a major part of the president's potential legacy," said Andrew Rudalevige, an associate political science professor at Dickinson College and author of "The New Imperial Presidency: Renewing Presidential Power After Watergate." "And the individual mandate does hold the substance of the package together, costwise and substantively."
A major initiative for a new president
When Obama signed the Patient Protection and Affordable Care Act into law in 2010, the move heralded a major -- albeit hard-won -- political victory for the president. The controversial legislation, which critics dubbed "Obamacare," extended coverage to 30 million Americans and was the culmination of a drawn-out and deeply partisan fight about the role of government.
For Obama, the law's passage proved his administration's ability to push through its policy agenda despite strong oppositional headwinds.
As Vice President Joe Biden told Obama after the law passed: "This is a big f---ing deal."
But netting that deal also cost the president tremendous political capital.
During the August recess of 2009, angry conservatives stormed congressional town halls to protest the legislation.
Repeal "Obamacare" became the rallying cry for a new wave of tea party-backed Republican House freshmen. Their massive sweep during the 2010 elections sent moderate Democrats packing and flipped control of the House of Representatives to the GOP.
Within months of the law's passage, the controversial law was in the courts. Conflicting appellate rulings ultimately led to the case being sent to the U.S. Supreme Court. Twenty-six states also pressed the Supreme Court to examine the law.
Energizing the tea party
Since the law was modeled after a similar Massachusetts measure, as the state's former governor, Romney, will face heightened scrutiny from conservatives determined to hold him to his campaign promises to repeal the law.
"I don't think there's an upside for the president here," said Ilya Shapiro, a senior fellow at the Libertarian-leaning Cato Institute and an expert on the Supreme Court. The ruling "energizes Republicans and the tea party."
Rudalevige added, "Romney will of course try to tie Obama back to the issue."
And Romney will have support from the Republican National Committee, which launched the website "PeopleVObamaCare.com" after the court's decision.
Romney press secretary Andrea Saul tweeted that in the hours after the ruling, the campaign raised $2.5 million online from more than 24,000 donors -- touting a hashtag, #FullRepeal, set up to promote their effort to overturn the law.
Reflecting after the ruling, Pelosi recalled the longtime dream of Sen. Ted Kennedy, a longtime champion of health care reform who died in 2009, a year before the legislation's passage.
"I knew that when he left us he would go to heaven and help pass the bill," she said from Capitol Hill. "And now he can rest in peace. His dream for America's families has become a reality."