What is a contested convention?

WASHINGTON — It is Donald Trump’s worst nightmare: the Republican White House nomination slipping through his fingers at the party convention in Cleveland in July, after dominating the months-long primary race.

Trump’s White House rivals Ted Cruz and John Kasich said on Monday they were teaming up to try to block him from an outright victory in Cleveland — if he does not have a majority of delegates, the GOP would find itself in a contested convention.

Republican delegates designated during the state-by-state primaries and caucuses held from February to June will choose the party’s candidate for president in Cleveland from July 18-21.

To seize the nomination outright, a candidate must reach an absolute majority of the delegates in play.

For the past four decades, the frontrunner has always reached the magic number — which this year is 1,237. But the strength of resistance to Trump’s candidacy — still challenged by Cruz, a US senator from Texas, and Kasich, the governor of Ohio, as well as the bulk of the Republican establishment — makes it possible that he may fall short.

That would result in what is known as a contested, or brokered convention.

When a candidate has an absolute majority, party delegates at the convention play a purely symbolic role, effectively rubber-stamping the results of the primaries.

But in the alternative scenario — if no contender can claim the crown outright — the nominee is selected through a series of ballots at the convention, in which the delegates acquire a critical influence.

For the first ballot, party rules in all but a handful of cases oblige delegates to back the candidate to whom they were pledged in the primaries.

Even if Trump does not have 1,237 delegates before the convention, a small number of uncommitted delegates could help him win in the first round.

But if no candidate has a majority in the first round, there is automatically a second ballot.

And that is where things start getting interesting.

“The majority of states free their delegates after the first ballot,” explains Josh Putnam, a campaign expert and political science lecturer at the University of Georgia.

That means those delegates could change their votes — and may gravitate towards an alternative candidate. The rules vary by state, and in Florida, for instance, delegates are only “released” on the fourth ballot. But according to The New York Times, 57 per cent of the delegates would be free to change their votes in the second round, and 81 percent would be freed in a third round.