Fight Over Delegate Rules Escalates for Both Parties

Voters have gone to the polls in droves during the Republican primaries, putting turnout on a record pace, yet the decision about who will be the ultimate nominee is increasingly likely to rest with fewer than 2,500 party insiders.

That has put GOP leaders in a historic and potentially explosive bind: Explaining that while Donald Trump has the most votes—some 1.9 million more than his closest rival—the rules could allow those officials to nominate someone else.

Democrats face their own challenges. Hillary Clinton’s commanding lead is built in part on party officials known as superdelegates, rather than raw votes.

As the pace of voting picks up, with New Yorkers heading to the polls Tuesday and balloting in five Eastern states next Tuesday, both parties face intense pressure to explain why the outcome of primary elections may be overtaken by party rules that give outsize powers to party leaders and delegates.