This doesn’t mean Biden can’t win. If he can replicate his performance among South Carolina black voters elsewhere, he will win in Alabama and could win in all of the other southern Super Tuesday states — Virginia, North Carolina, Tennessee, Arkansas, Oklahoma and Texas. If the media attention he will receive also moves some centrist white voters away from candidates such as former mayors Mike Bloomberg and Peter Buttigieg, he could win many of these states by convincing, if not landslide, margins. But he is still highly unlikely to win them by large enough margins to offset the huge delegate advantages Sanders will likely obtain in the white, liberal and secular states.

If this happens, Biden will be facing the same uphill struggle Hillary Clinton faced in her 2008 campaign against Barack Obama. She won many of the later voting Midwestern states such as Pennsylvania and Ohio. But even winning these states by nine or 10 points couldn’t give her enough delegates to offset the delegates Obama was getting from smaller, more progressive states such as Oregon and Wisconsin. Under the Democrats’ system of awarding delegates in proportion to the popular vote, it is very hard to catch up once you fall behind.

That makes a contested convention Biden’s best hope of becoming the nominee.