Transcript for How a raucous convention revolutionized our primary system
The way that we choose presidential candidates in the United States is pretty unique in most countries the parties themselves are responsible for choosing whoever they want their candidates to. In the United States we ask voters to decide. But our primary system isn't in the constitution. It exists because of something that happened in 1960. At the Democratic National Convention. For the majority of American history most states didn't have primaries and the primaries that did exist. We're not like the ones we have today they were basically like straw polls. Non binding votes that whole party leaders which candidates were electable. But party leaders didn't have to listen to the voters instead delegates from each state would meet at the national convention. Reeling deal and eventually land on a presidential nominee. That was still the case in the late sixty back then the Democratic Party was deeply divided. He was divided over the war in Vietnam it was also divided over the civil rights and the months leading up to the Democratic National Convention. We're very small us. First president Lyndon Johnson decided not to run for re election. I shall not see. And I will not accept. Denomination on my party for another term as your first. Then Robert Kennedy an anti war front runner was tragically at south. We are great country. That countries and a compassionate. Eyes and make like a money. And there were true main contenders vying for the nominee. Hubert Humphrey the establishment candidate and Eugene McCarthy's anti war. Anti war activists realized that if they couldn't get a bunch of delegates who supported Eugene McCarthy to the convention he wasn't gonna get nominee. Now if this happened under this system that we take. McCarthy's supporters would just need to get a bunch of people to go out and vote for McCarthy in the primary in order for him to win an Banesha. But that's not how things work. Even if save 50% of its state supported Eugene McCarthy that didn't mean it U percent of the State's delegates. Would actually go to the convention to vote from. This upset a lot of McCartney's. And it sat on the power to change the Democratic Party rules for selecting the nominee. NYPD and the invaders will not be seen tonight so that ABC news could bring new color coverage. Of the 1968. Democratic National Convention. And. This all came to a head at the Democratic National Convention in 1968. In Chicago. Which was an absolutely did asked. Outside the convention hall there was basically a rise but inside the convention hall with pretty chaotic as well. Famously Dan rather the reporter got punched in the stomach on national element. It was a whole fiasco mob they're getting. Which and essentially. Because Hubert Humphrey how the support a party insiders. He ended up winning the nominee. The anti war part of the democratic primary was pretty upset with how the whole picture. They put. Forward a proposal to change the rules of the Democratic Party so that the delegates that go to the national convention after fairly reflect the preferences. Of the people in the state when he came. It's debated whether or not a lot of the delegates on the actually even understood what they were voting. But they passed it nonetheless. And it amounted to a complete overhaul of the party nominating system in America. What happened next is the Democrats lost the 1968 election to Richard. And in the aftermath of that they created a commission to put the new rules into effect and those new rules will almost surprisingly effect. By 1970 Q every state in the country has implemented in do walls that the party. All future state delegations would have to reflect the preferences of voters in that's. And the changes didn't just divided Democrats. The new rules require changing state laws. So Republicans eventually ended up adopting those changes as well creating the primary system we have. On its face this new system seems a lot more Democrat. The nominees are no longer chosen in these proverbial smoke filled. Know the voters get to this. But has with a lot of things in American politics it's a lot more complicated. In the next few Pappas we're gonna look at the consequences. Both intended and unintended. Of those changes that began in 1960. Come back next week to learn more about our primaries. And make sure you subscribe below so you never miss Nvidia. For even deeper dive on the American primary system check out the 538 politics pod cast. We have a three part series all about it. Mall.
This transcript has been automatically generated and may not be 100% accurate.