Why is it important?
A contested convention occurs when no individual candidate has a winning majority of delegates before the nominating convention begins. If that happens, most delegates are free to vote for any candidate—and can coordinate to agree on a nominee. This is also sometimes anachronistically called a "brokered convention."
But most importantly, contested conventions call into question the primary process itself. For many, the idea that the nominee may not receive most—or even any—of the primary votes is antithetical to the democratic process.
Should Republican party leaders push for a contested convention?
The idea that voters this year might decide on a candidate, send delegates to the convention, and those delegates coordinate to elect someone else, is unconscionable.
First, it ignores voters' clear choice. It shouldn't matter what top Republicans think of a candidate. It shouldn't even matter whether that candidate earns more than half of a highly splintered voter base. If the candidate with the most primary votes doesn't win the nomination, it is a direct insult to voters across the country.
Second, it would do immense damage to the Republican party. Voters are already obviously frustrated with a party establishment they feel is not listening to them. A contested convention would confirm this feeling in the worst possible way and alienate many from their own party.
Third, there are no other realistic options. Rule 40b, adopted this year, says any convention candidate must have won a majority of delegates in at least eight primary contests. Though there has been talk of a surprise candidate like Mitt Romney or Paul Ryan, the new rule effectively prevents this. In fact, not even Ted Cruz or John Kasich have yet met this mark.
Those who argue that contested conventions are undemocratic are missing the fundamental point of the nominating process.
We choose nominees (and, for that matter, presidents) not purely through popular vote but through a combination of three factors: what candidates are presented, who people vote for, and how those votes are cast and counted. And that's a good thing.
If Donald Trump wins a majority of delegate votes, he wins the nomination regardless of any effort towards a contested convention. But if he doesn't, the process of how votes are counted makes all the difference.
The plurality rule—that the candidate with the most votes wins, even if not a majority—is only one way of democratically counting votes. Consider the instant runoff rule, in which the third candidate is eliminated and his or her votes are cast for voters' second choice. It's all a matter of process—which is exactly what a contested convention recognizes.
Without a majority, Trump is not the obvious "democratic choice." And he shouldn't be. We should have a contested convention.