Obamacare has faced multiple serious challenges. Pivotal Supreme Court decisions. Dozens of congressional votes to repeal the Affordable Care Act. National elections that could have doomed the healthcare legislation. A disastrous launch of the federal health insurance exchange.

Despite it all, Obamacare is still here. Proponents say it's here to stay. It's quite possible, though, that one area where healthcare reform has seemed to achieve success could be one of the biggest potential problems of all.

This huge potential issue for Obamacare could definitely impact the national political scene. It could also significantly affect several healthcare stocks. Two managed care companies might be especially at risk -- Centene Corporation (NYSE: CNC) and Molina Healthcare (NYSE: MOH). 

Both Centene and Molina are riding high right now. Centene's stock is up nearly 98% over the last 12 months. Molina isn't far behind, with gains of 88% during the same period. Wall Street expects the companies to keep the momentum going for years to come. 

But the problem that looms large for Obamacare in just a few years could hurt Centene and Molina. Watch the slideshow below to see three charts that paint the picture of what could be the biggest remaining hurdle for Obamacare.

The next billion-dollar iSecret
The world's biggest tech company forgot to show you something at its recent event, but a few Wall Street analysts and the Fool didn't miss a beat: There's a small company that's powering their brand-new gadgets and the coming revolution in technology. And we think its stock price has nearly unlimited room to run for early in-the-know investors! To be one of them, just click here.