Trump and Cruz could split the GOP vote. Here's what a brokered convention would look like.

As Donald Trump and Ted Cruz continue to split Republican primary votes, political analysts are becoming increasingly frenzied about the possibility of a "brokered convention": one where no candidate gets a majority of delegates, leaving the party elite to pick a nominee (presumably, in this case, not Donald Trump).

"We could be headed to a situation where there will be tremendous focus on trying to have a brokered convention — or a deadlocked convention because there aren't any brokers," former Mitt Romney strategist Stuart Stevens recently told NPR.

A brokered convention is what happens when no candidate has accrued a majority of delegates through the primary process. And political pundits love to speculate about them because they just sound dramatic and exciting. One brokered convention in the 1920s required more than 100 rounds of voting to settle on a nominee.

"If no nominee is elected after first ballot, all hell breaks loose," says Elaine Kamarck, author of Primary Politics: Everything You Need to Know About How America Nominates Its Presidential Candidates.

Brokered conventions are rare — the last one happened in 1952 — but this year, it's not a totally out of the question. Here's why.

Up through the mid-20th century, brokered conventions were relatively common. The nomination system was pretty much controlled by party elites, leaving the general public largely in the dark. Some states held primaries; others didn't. That would leave the decision of whom the states' delegates would vote for largely up to local political leadership.

There weren't any rules about whether delegates actually had to vote for whom they'd been told to support (that's since changed — more below). So there were fewer barriers to convincing delegates to change their minds.

Take 1948, when then–New York Gov. Thomas Dewey sought his second bid at the Republican nomination. (He lost his first bid in 1944 to Franklin Roosevelt.) After three rounds of voting, Dewey and his allies were able to woo enough delegates to clinch the nomination. Although, as the infamous photo reminds us, Dewey's efforts were ultimately for naught — he was unable to defeat Truman.

There hasn't been a brokered convention since 1952. Will 2016 be the year?

This year, obviously, things are a bit different. Primary reforms in the 1960s now require party delegates to vote for whomever their state directs them to (unlike in 1948, when a Dewey delegate could simply change his mind to Roosevelt, ignoring any vote his state may have taken). You can read more about those reforms here, but the main thing to know is this: Modern primary rules make it much harder for party elites to sway votes and broker deals.

But in this current election, that might not stop a brokered convention from happening anyway.

Currently, Trump leads the other candidates in race for delegates by sizable margins. There is a lot of space for things to change, though, particularly next week, when battleground states Florida and Ohio hold their "winner-take-all" primary contests.

If Trump wins Florida and Ohio, it's possible that brokered convention speculation will diminish. But if he doesn't — if, for example, both Ohio Gov. John Kasich and Florida Sen. Marco Rubio win their home states — then it could potentially set the stage for a convention where no candidate has a majority of delegates.

The last time we came close to a brokered convention was the 1970s

While the modern primary system has not seen a brokered convention, both the Republican and Democratic parties have come close. In 1976, Ronald Reagan challenged then-President Gerald Ford for the presidential nomination in a preliminary, nonbinding vote known as the Mississippi Challenge to see if he could sway delegates to vote for him instead of Ford.

Kamarck, who is a superdelegate for the Democratic Party, told me a vote like the one Reagan posed is nonbinding and used to test the strength of the convictions of the candidates. She said the purpose of the vote is for challengers to assess how strongly committed delegates are to their respective candidates. And in the case of 1976, Reagan was unable to secure the needed vote to pose as a serious threat to Ford, so he gave up his bid and a brokered convention was avoided.

Similarly, leading up to the 1980 Democratic convention Sen. Ted Kennedy engineered a test vote to determine if he could pull delegates away from President Jimmy Carter, who was seeking reelection. When Kennedy found he couldn't sway delegates pledged to Carter, he withdrew, and Carter was elected as the nominee on the first ballot, avoiding a brokered convention.

So even though a brokered convention hasn't happened in the post-reform era of the primary system, we continue to obsess with each presidential cycle whether this will be the election that finally witnesses one. And the intrigue largely stems from the fact that if a brokered convention were to happen, it would make for good political drama, as it speaks to internal divisions and factions in the party and backroom deals and bargains.