The American presidential primaries have been playing out for six weeks — and they are not even close to being over. 

That is because the outcome will remain uncertain for another three months — or even until July, when the Republican Party could have to hash things out on the convention floor in Cleveland, Ohio.

Hillary Clinton is well on her way to securing the Democratic nomination. But the path for Donald Trump will almost certainly run through California, New Jersey and the other states voting in the last set of primaries on June 7.

The results of Tuesday's primaries were very positive for Clinton. She beat Vermont Senator Bernie Sanders in all five states on offer, though the two finished in a virtual tie in Missouri. For the Democrats, however, it isn't about winning states but rather about winning votes. The delegates for the party's nomination are awarded proportionately, and Clinton's edge over Sanders continues to grow as she runs up big numbers in the American South.

Votes in almost half of the states still need to take place before Clinton clinches the nomination, but whatever tension remained in the race has run out.

Not so on the Republican side.

Donald Trump was the big winner on Tuesday, taking four of the five states. John Kasich won Ohio, where he is the sitting governor. Texas Senator Ted Cruz held Trump to a very narrow margin in Missouri.

But Trump still won about three-fifths of the delegates awarded on Tuesday, thanks to his big wins in the winner-take-all state of Florida and the winner-take-most state of Illinois.

Donald Trump vs. Hillary Clinton2:58

Rubio out, but where do his voters go?

The impact of Trump's win in Florida went beyond the 99 delegates he captured. It also forced out Senator Marco Rubio, who was hoping for a win in his home state.

Though Rubio never pressed Trump very much in the polls, he was the party establishment's favourite and was seen by many as the last viable candidate that the party could put up against Clinton for the general election in November.

Before he dropped out of the race, Rubio was sitting on around 18 to 20 per cent of the vote nationwide among Republicans. Those are supporters who the three remaining candidates are salivating over. Kasich, as the last "mainstream" Republican on the ballot, may hope to corral most of Rubio's voters. Cruz, more ideologically aligned with Rubio, may also have a strong claim on those votes.

Trump, who took delight in belittling and insulting the Florida senator, is unlikely to gain much from Rubio's departure.

But Rubio's voters may not number enough to single-handedly transform the race.

Kasich would not have won another state on Tuesday had every Rubio vote gone to him, while Cruz would have only prevailed in North Carolina and Illinois if almost every Rubio voter had gone his way instead. Both candidates will have to peel support away from Trump in order to make any major inroads.

Future brutish, long for non-Trumpians

They do have some time, as the pace of the primaries will begin to slow. After 29 states voted in six weeks, the next six weeks will see only 10 states cast a ballot in the Republican race. Many of these states are likely to favour Trump, including his home state of New York, as well as other states such as Arizona, Wisconsin, Maryland and Pennsylvania.

However, the campaign that is tearing the Republican Party apart at the seams will not come to a merciful end any time soon.

Trump would have to win every winner-take-all state and about two-thirds of the vote in the proportional states to win a majority of delegates before the final day of voting on June 7.

More realistically, June 7 will be the decisive date — and it could be a near-run thing.

Trump ended the night on Tuesday with almost 700 delegates, followed by Cruz at around 400 and Kasich at around 150. Rubio had about 170 delegates when he suspended his campaign.

Overall, Trump has won just under half of the delegates that have been awarded so far in the race.

The delegate math is tight for Trump, but a path to a majority does exist for him. It runs primarily through California and its 172 delegates, which can be won in their totality if Trump gets good enough results throughout the state.

It is a key state for him, as a look at the map with some reasonable estimates of likely delegate results suggests that he can win a majority even if he loses a number of the winner-take-all or winner-take-most states still left on the calendar.


John Kasich, left, and Ted Cruz are the only other Republican candidates still in the race. (Joshua Roberts/Reuters, Rogelio V. Solis/Associated Press)

If Ohio Gov. Kasich wins in Pennsylvania and Indiana, two states bordering his own, and Cruz wins in Nebraska, Montana and South Dakota, states he might be expected to do well in, Trump could still just get to the 1,237 delegate mark with about 45 per cent of the vote in the states that award their delegates proportionately.

However, every one of those five states above that Trump wins gives him more room for manoeuvre in the proportional states.

It all comes down to Cleveland

But this is all about denying Trump a majority of delegates. Cruz would need to do implausibly well in the remaining races in order to win a majority on his own, while there aren't enough delegates still to award to get Kasich over the 1,237-delegate mark.

The path to the Republican nomination for these two men, then, runs through the convention floor in Cleveland. By keeping Trump to a minority of delegates, they can hope to overtake him after the first ballot and be the consensus choice among attending delegates.

Whether that would prevent Trump from running for president as an independent is another matter entirely. And it is still unknown whether the Republicans will unite behind a Trump candidacy or splinter off in favour of a more "mainstream" conservative candidate.

Even if Trump manages to secure a majority of delegates by the end of the primary season, the drama, be it a comedy or tragedy, will likely stretch long into the summer for the Republicans — and maybe right through to election day in November.