The spotlight on President Obama's health care overhaul will intensify in coming months as states and businesses gear up for sweeping changes that could determine whether the public embraces the president's signature legislative achievement or decries it as government overreach.

After the U.S. Supreme Court upheld the new health care law, the politics evolved from arguments over the reforms' constitutionality to a debate over whether the massive system can be implemented effectively.

The president has long assured critics that once the reforms are fully enacted, the public will embrace them. Yet, while voters gave Obama a second term in November, polls show they are wary of the looming changes. A Rasmussen poll last month showed that nearly half of the respondents expect the health care system "to get worse over the next couple of years."

The individual mandate, a key provision that requires all people to buy insurance or pay a penalty, won't kick in until 2014. But states are already creating insurance exchanges and enrolling residents. Higher taxes on medical devices, capital gains and dividends rose on Jan. 1 as a result of the health care reforms.

Some businesses are already altering their hiring practices to prepare for the looming changes. Any company with more than 50 full-time workers must offer health insurance to employees who work more than 30 hours a week, so employers are moving more workers to part-time status.

"This has now shifted to being a practical deadline," said Edmund Haislmaier, a senior research fellow on health policy studies at the Heritage Foundation. "We have nine months before this goes live. If you're not ready, the wheels really start to fall off."

Given the political opposition and public doubts about the reforms, Obama is eager to change public perceptions. Analysts say he needs to launch a public relations campaign much like the one that helped him build public support for a tax increase on the wealthy.

"He's going to have to talk about it more to reduce the angst over the program," said Democratic strategist Hank Sheinkopf. "Look, there will always be a resistance. It's hard, and some small businesses won't be happy -- that's life."

Obama must convince young, healthier people in particular to get health insurance. Their participation is critical because it would make coverage more affordable for those more prone to sickness.

The White House also must combat Republican charges that the new law will cause an increase in premiums, the loss of employer-based health insurance and endless bureaucratic interference with the health care system.

Administration officials will try to highlight some of the law's more popular provisions, including one that allows children under age 26 to remain on their parents' health care plans and another that prohibits insurers from denying coverage to those with pre-existing conditions.

The stakes couldn't be higher for Obama, whose presidency could be judged by the success or failure of the most comprehensive overhaul to the health care system since Medicare was created in 1965.

"His legacy is on the line," said a top Democratic consultant. "If this thing doesn't work, he'll have the world's largest egg on his face. There are a lot of hurdles to clear, and it's imperative that he doesn't stumble out of the gate in these early stages."