Since there seems to be a lot of TRUMP-PHOBIA at the moment, I thought I would attempt to write out an explanation of our process.
There are 2 major parties. Democrats (approximately = Labour) and Republicans (approximately = Tories). Each party has certain subgroups that traditionally find their voice within that party, as we do not have a parliamentary structure that allows non-affiliated subgroups to have their own independent representation.
We hold elections every 2 years, with all members of the House of Representatives (= lower house) standing for election. Additionally, 1/3 of Senators (=House of Lords) stand for election to a 6 year term. Every 4 years we elect or a President (who may serve no more than 2 terms). This results in some national elections (like this one – 2016) being more “influential”. A popular or unpopular presidential candidate can result in gains or losses “down” the ticket (for Senators and Representatives). Therefore, these more important elections tend to have more vitriol to whip up the fervor.
Now – to the process.
Each party may begin selecting a candidate for president (and also Representatives & Senators if there is an intra-party contest) in January of the year of election. The first state to do so is IOWA, followed by NEW HAMPSHIRE. Shortly behind them is SOUTH CAROLINA. This provides some otherwise minor states (in overall electoral strength) to serve as an early indicator for that region (IOWA representing the MIDWEST. NEW HAMPSHIRE representing the NORTH EAST, and SOUTH CAROLINA representing the SOUTH).
In each of these states, the selection of a national party nominee begins, but in a different manner. A state may hold a CAUCUS (IOWA), whereby the party controls the voting process for that party, and can set the rules. A state may also hold a PRIMARY where the state election board sets the rules. A PRIMARY may come in one of three flavors – OPEN, CLOSED, or MIXED. A CLOSED primary allows only those voters registered as a member of a specific party to vote on that party’s ballot. As such, this tends to be the party loyalists who are usually farther left or right than the electorate as a whole. An OPEN (SOUTH CAROLINA) primary allows ANY REGISTERED VOTER to vote on a ballot – so crossover voting may occur. MIXED (NEW HAMPSHIRE) allows anyone registered for that party or as an independent to vote.
From these CAUCUSES or PRIMARIES delegates are awarded or assigned, with one caveat (UNPLEDGED or SUPER DELEGATES - I'll abbreviate as SD). The Democratic Party has approximately 4700 total delegates, with 2383 required to clinch the nomination. The Republican Party has approximately 2500 delegates with 1237 being required to clinch. These numbers do not reflect the relative number of registered voters (There are NOT 2X more Dems than Repubs nationally registered) but is a number that is determined by the national party. Prior to March 15th, delegates are normally awarded in a proportional manner. From March 15th onward a state’s party may choose to award all of their delegates in a Winner Takes All fashion. This date is chose because at this time one or two nominees are usually the only viable candidates left and it accelerates the nomination process.
Unpledged Delegates (aka SDs) are “party faithful” that are afforded delegate status based on their position (members of congress, state governors, etc…..). These constitute 6.5% of the Republican delegates and 15% of the Democrats. One particular and very un-Democratic quirk is that the Democratic SDs are not required to vote as their state voted. So, in the case of NEW HAMPSHIRE, where Sanders won by a large majority, Clinton came away with more delegates because she wooed the entire slate of SDs. This is why she appears to have such a substantial, even insurmountable, lead over Sanders in delegates when the margin of separation for percentage of votes cast is much narrower.
In early Summer each party holds a National Convention. For a candidate that has already acquired the delegate count to clinch the nomination, this is a time for the party to select a Vice Presidential candidate (often from the second runner up subgroup within that party) and unify around their national ticket. This is when they will also begin electioneering for Senate or House candidates in their party. Also during the CONVENTION we see a swing back towards CENTER politics. The primaries play to the staunchest party members, while the national election seeks to bring in independents voters, undecided party voters, and dissatisfied crossover votes from the opposing party.
In the event that a CONVENTION meets and no single candidate has acquired the necessary votes to clinch the nomination, a brokering process begins. In some cases, after the first vote fails to make a choice, all or some candidates are released from their candidate obligation and are allowed to vote for who ever they choose. This is when a 2nd and 3rd place candidate could conceivably join forces to share delegates and overcome a 1st place candidate. Also, a lower tier candidate could trade their delegates for a promised cabinet post in the leaders administration. It is at this point our system probably most closely resembles yours.
If I have erred on certain points I will ask Muir and Southern to help me correct or clarify those.
Hope this helps.