Going for brokered: what is a brokered convention and why are anti-Trump Republicans praying for one?

Republican delegates designated during the presidential primary process will choose the party’s candidate for the November election at a nominating convention in Cleveland in July.

But frontrunner Donald Trump’s rivals are hoping to prevent him from achieving the majority of delegates needed to seize the prize - a situation that would result in a brokered convention. Anti-Trump grandees like Mitt Romney are pinning their hopes on this outcome.

For the past four decades, the frontrunner has always reached the magic number of delegates needed to win the nomination prior to the convention - this year, 1,237 out of 2,472.

But if Trump falls short,

the outcome would be what is known as a brokered convention in which the delegates - who normally play a purely symbolic role, effectively rubber-stamping the results of the primaries - acquire a critical influence over the nomination.

For the first-round ballot, party rules oblige delegates to back the candidate to whom they were pledged in the primaries. Those tied to candidates no longer in the race, such as Marco Rubio and Jeb Bush, would not vote.

But based on the results of the primaries, that first round would not produce a majority, and the vote would go to a second round.