Republican presidential candidate Donald Trump speaks while visiting a caucus site, Tuesday in Las Vegas. (AP Photo/Jae C. Hong)

With Super Tuesday results rolling in tonight, we thought we'd re-up this great post from Elaine Kamarck about the importance of the second, mini-Super Tuesday on March 15.

It may not seem like it, given all the noise and drama, but the fight for the presidential nominations in both parties has just begun. The four early primary states have done what they always do – weed out weaker candidates and shape the field -- but these small states don’t begin to tell the story. So far, the Republicans have allocated only six percent of their delegates to their convention, and the Democrats have allocated only four percent. The month of March will tell us a lot more about the race for the presidency as the delegate count begins in earnest.

Nominations have been won and lost when presidential candidates have lost sight of the fact that the ultimate goal is getting 2,408 delegates to vote for you at the Democratic convention and 1,237 delegates to vote for you at the Republican convention. By the end of March, which is heavy with primaries in medium-to-big states, the Democrats will have selected 56 percent percent of their delegates and the Republicans 64 percent. While it is likely that no one in either party will have enough for a first-ballot nomination by the end of March, we will have a pretty good idea of where the race is going and whether or not we’re headed for that fabled “brokered convention” in either party.

The fight for delegates is governed by party rules – not state statutes – although sometimes they are one and the same. Understanding the Democratic side is easy (sort of) in that the rules in every state are the same. After decades of fighting about it, the Democrats adopted a blanket rule in 1992 requiring that delegates be awarded to presidential candidates on the basis of proportional representation. This came at the insistence of the Rev. Jesse Jackson, who had failed twice to win the Democratic nomination in 1984 and 1988 and was angry at being cut out of as many delegates as he thought he deserved.

Republicans, consistent with their overall federalist philosophy, give states much greater leeway in deciding how to award delegates to presidential candidates, but they too have gotten into the business of dictating rules from above. This year, states holding their contests March 14 or earlier must use a proportional system; after that date they can choose how to award delegates to candidates. This is why there is a big “Super Tuesday” on March 1 but also a kind of mini-Super Tuesday on March 15.

So what does this mean as we move forward? Well, it’s important to note that the Democrats’ rules are much more proportional, while the GOP puts a higher premium on winning states and awards fewer delegates to losers.

On the Democratic side, the structure of the rules rewards losers relative to winners.  The way the delegate math works in every congressional district in the country, the winning candidate has to have a very big win in order to win more delegates than the losing candidate – especially in a two-person race. That’s because the Democrats don’t reward fractional votes and the rounding rules end up favoring the loser. In a district with an even number of delegates, the winner must win over 62.5 percent of the vote in order to win three delegates out of four or four delegates out of six.

These rules have had an impact on more than one Democratic race for the nomination. Take, for example, the 2008 race in Ohio. Hillary Clinton won a solid victory there over Obama, and yet her 10-point victory netted her only 75 delegates, while Obama picked up 66 delegates.

On that very same day -- March 4, 2008 -- in the other party, John McCain was clinching the Republican nomination. He won 60 percent of the vote in Ohio, but because of winner-take-all rules, he won all the delegates from that big state. In fact, Mike Huckabee, the closest vote-getter to McCain on the Republican side, finished second in 16 primaries in 2008 and netted only 74 delegates out of all 790 in those states. Winner-take-all rules, forbidden on the Democratic side but favored on the Republican side, have exactly the opposite effect of the Democratic rules; they favor winners over losers.

After the 2008 race, in a rare outbreak of bipartisan cooperation, both political parties searched for a way to get states to stop moving their primaries earlier and earlier in the election year. Punishments, such as cutting the number of delegates for an offending state, had failed to have much impact, so the two political parties turned from sticks to carrots. On the Democratic side, the “carrot” was more delegates for states that stayed later in the spring -- something that appealed to a party always concerned with greater participation. On the Republican side, the “carrot” was the ability to hold a winner-take-all primary, but only if it was held after March.

The “carrots” worked wonders. The 2012 election had the fewest number of delegates selected before March in a decade. In 2016, the Republicans kept their prohibition on early winner-take-all primaries but moved the date after which they could be held back to mid-March.

As the mid-March date looms, Republicans are increasingly in a panic to clear their field for a consensus Anybody-But-Trump candidate. And for very good reason: There are 23 primaries and caucuses between March 1 and March 15. Although Donald Trump is running ahead in most of those states, the delegates will most likely be spread among the candidates unless Trump manages more substantial wins than he has had to date. In other words, for the first half of March, the Republican delegate count will look more like the Democrats’ delegate count in that even the losers will win some delegates.

But while the Democrats may be doomed to fighting for delegates throughout the spring, the Republican race will change dramatically on March 15. On that day, five big states – Florida, Illinois, Missouri, North Carolina and Ohio -- will hold primaries, and all but one will be either winner-take-all or some sort of hybrid system that could also yield a winner-take-all outcome. These five states (and one territory also voting that day) account for 367 delegates – many of which, again, could go in a lump sum to one candidate -- while the 12 states voting on Super Tuesday account for 624 – and will, again, be divvied up proportionally. In other words, March 15 could feasibly see a bigger swing than March 1.

If the Republicans have not coalesced around an “Anybody-but-Trump” candidate by March 15, of course, he will be well on his way to a first ballot nomination at the Republican National Convention.

Time is running out.

Elaine Kamarck is a senior fellow at the Brookings Institution and the author of "Primary Politics: Everything you need to know about how America nominates its presidential candidates."