Under current Democratic rules, Clinton has 1,662 pledged delegates and Sanders has 1,373; that’s a lead of 289 delegates.3

This means that Sanders has won a larger share of the pledged delegates (45.2 percent) than of the popular Democratic vote (42.3 percent). David Wasserman recently explained that this gap exists partly because some of Sanders’s best states have used caucuses instead of primaries, and turnout is lower in caucuses, where it’s harder to vote.

So what’s the takeaway? The Democrats’ delegate allocation rules are more “fair” than the GOP’s rules in the sense that vote shares are translated into delegate shares more faithfully and uniformly — but aspects of the process, such as the use of low-turnout caucuses and some delegates getting allocated based on the results of subsequent conventions, can distort that translation. If the Democrats used Republican allocation, Clinton would have wrapped up the nomination long, long ago. If the Republicans used Democratic allocation, we’d almost assuredly be heading toward a contested Republican convention.