If Biden’s black support holds up that long, he will have prevented Sen. Bernie Sanders (I-Vt.) from locking up the nomination before the convention. Democrats award their delegates according to a candidate’s share of the popular vote, so long as that person received at least 15 percent either statewide or in a congressional district. If Biden has locked up the black vote and former New York mayor Mike Bloomberg and former South Bend, Ind., mayor Pete Buttigieg are each breaking 15 percent of the white vote, then Sanders will not have a large delegate lead after four states vote on March 17. More than 61 percent of the delegates will have been awarded by that date; Sanders cannot win the remaining states by large enough margins to give him a majority before the convention.

This means Biden can go into the convention with a good shot of winning because of his support among the Democratic establishment. These party leaders comprise the uncommitted superdelegates, who also will attend the party convention. They won’t be allowed to vote on the first ballot, but they can vote on any ballot after that if the convention is deadlocked. Biden’s black support will ensure such a deadlock if it holds up, and then the establishment can rally behind the man they always hoped would lead the ticket. Gamblers know that the odds are almost always with the house, and in the Democratic Party, the superdelegates are the house.