What led to the fall of national convention?

Answer 1

It's almost certainly that a group of people decided to convene.

If you're thinking of the Democratic or Republican National Conventions, there's no actual legal requirement for them. The Democrats and Republicans decided to respectively to hold a convention, so they do. The leaders of the respective parties could ... entirely legally ... simply announce their party's candidate based on a coin flip or whatever, and the only thing you could do about it if you didn't like it is not vote for that party anymore.

For that matter, the US Constitution makes NO PROVISION WHATSOEVER for the existence of political parties, meaning that there are also no restrictions on them other than as otherwise provided for by law; they can choose their candidates however they like provided they don't break any other laws in the process (they can't, for example, perform a ritual murder and read the entrails of the victim to decide the candidate, because murder is illegal, and in most places the remainder of the process would fall afoul of laws against "desecrating a body").

If that bothers you, you may be even more upset to find out that the federal government is not actually required by the constitution to pay any attention whatsoever to the popular vote for president. Instead, it says that the individual states (specifically, the legislature of each state) gets to choose the electors who really determine who's going to be president, and that they can do it in any way they like. If they WANT to hold a popular vote and decide that way, it's fine, but if they want to do it some other way, that's ALSO fine. For the first few presidential elections, several states just had their state congress pick the electors directly. In my home state, for most of the 20th century even though you voted in the presidential election, you technically were not voting for a presidential candidate but instead for an elector who had pledged that, were he to become an elector, he would vote for a particular candidate. And what could you do if he instead voted for someone else? Most of the time, bupkis (a few states have enacted laws against it, but none of them have ever actually been enforced). There's an official term for this ... "faithless elector" ... and it's actually happened several times: 157 so far, though it's never made any difference in the actual outcome of the election. The closest it's ever come is in 1836, when no fewer than 23 electors decided together to prevent Richard Johnson from winning the vote for Vice-President. In practice, though, this just meant no one got a majority, so the US Senate got to decide, and they promptly elected Johnson anyway.