Sen. Elizabeth Warren is not a viable candidate to win the Democratic presidential nomination outright. The Massachusetts Democrat has suffered humiliating losses in early primary contests and even lost the primary in her neighboring state of New Hampshire. She’s about to get crushed again, this time in South Carolina. Yet it’s still entirely possible Warren could end up the Democratic nominee.

So what exactly is Warren’s path to the nomination? A brokered convention, where establishment Democrats and the activist base settle for her as a compromise candidate. This may be why Warren isn’t dropping out.