The Supreme Court just upheld the Affordable Care Act as constitutional, affirming Congress’ authority to require Americans to purchase health insurance coverage.

It’s no doubt an understatement to describe this as a huge victory for the law, and the Obama administration. The Affordable Care Act - after spending two years in legal limbo - now has the court’s backing to move forward. That does not, however, mean the law has smooth sailing ahead. Many obstacles still stand in the law’s way, ones that could derail its success nearly as much as an adverse legal ruling. Here’s a rundown of what the law faces in coming months.

The 2012 elections. Former governor Mitt Romney (R) has repeatedly pledged that, if elected, he would repeal Obamacare on his first day in office. While Congressional procedure pretty much makes that impossible, there is still a lot a Republican president could do to impede or slow the implementation of the Affordable Care Act - especially if he happens to be working with a Republican-controlled Congress.

“This definitely raises the stakes for November,” says Cheryl Smith, a director at health consulting firm Leavitt Partners. “That would be the last opportunity to elect a Congress that could put this back in the hands of a state.”

Repeal isn’t exactly easy: There would be a lot of procedural hurdles to overcome for a President Romney who wasn’t working with a supermajority in the Senate, and had to use reconciliation (more on that here).  Administratively though, there’s decent leeway to move slowly on implementing the Affordable Care Act, or devote fewer resources to making sure it works than an Obama administration may have.

The states. States hold a huge amount of sway with what happens with the Affordable Care Act. They’re the ones doing the heavy lifting in setting up health insurance exchanges, the marketplaces where an estimated 32 million Americans will purchase health coverage beginning in 2014. How well those health insurance exchanges work is nearly certain to impact the size of the insurance expansion, with an easier-to-use system likely leading to bigger numbers.

Some have moved aggressively on implementation; others have refused to do anything. Today’s decision could encourage states to move faster, as many have said they were waiting for the Supreme Court to rule before devoting resources to implementation. There’s also the possibility though that states could wait for the results of the November election. And that would mean less prep work for the law’s big launch in 2014 - that’s when pre-existing conditions end and the individual mandate starts - and a less solid foundation.

Public opinion. The Affordable Care Act has been divisive since it became law, with public opinion polls regularly finding the American public leaning against the overhaul. With the law’s least popular provision left standing - the individual mandate - that’s unlikely to change anytime soon.

That could become a roadblock for the law’s biggest goal: Getting Americans to sign up for health coverage. In Massachusetts, where the individual mandate was very effective in increasing coverage, the law had a broad base of public support. Jonathan Gruber, the M.I.T. economist who worked on both the Massachusetts and federal laws, says that negative public opinion has the potential to make the federal experience less smooth.

“There’s certainly a risk that a large opposition could mitigate the effects of the mandate,” says MIT health care economist Jonathan Gruber, who worked on both the Massachusetts and the federal law. “I could see some resistance, where people decide to pay the fine.”

That would be bad news for the Affordable Care Act: The whole point of the mandate isn’t to raise revenue, but to make sure that healthy people buy insurance. If only those who anticipate high medical needs enroll, premiums could spike.