1237 delegates to clinch the nomination or force a contested convention
Donald Trump's delegates: 996 - he is 241 away
Others' delegates: 905 - If the delegates won by Ted Cruz, John Kasich, Marco Rubio and others are combined they are 332 away
Donald Trump is the last candidate with a true shot at winning the Republican presidential nomination before the Republican National Convention in July.
To clinch the nomination, he must win a majority of the delegates.
But if he doesn't - in other words, if everyone else combined wins a majority of the delegates - there will be no nominee heading into the convention.
In this sense, the race has shied from a free-for-all to a more direct contest: Trump versus everyone else.
With fewer than 600 delegates left unallocated, and some wiggle room in those already allocated, this is the race to watch: Will Trump reach 1237 delegates, or will everyone else?
Forty-one of Trump's delegates are unbound, meaning they are not locked into Trump.
Much like "superdelegates" on the Democratic side, unbound delegates may vote for any candidate and can change their minds at any time.
The bulk of Trump's current delegates are bound, though, meaning they must vote for him on the first ballot at the convention.
More than 200 delegates are either unbound or allocated to a candidate who has dropped out. Some of these delegates will be free to vote for any candidate on the first ballot at the convention.
States have different rules and interpretations directing what happens to delegates bound to candidates who are no longer in the race. Some of these determinations remain unclear.
It is possible that a delegate bound to Marco Rubio, for example, could be released and subsequently vote for Trump on the first ballot.
STILL TO COME
May 4 Indiana 57 delegates
May 11 Nebraska 36; West Virginia 34
May 18 Oregon 28
May 25 Washington 44
June 8 California 172; Montana 27; New Jersey 51; New Mexico 24 South Dakota 29
Unallocated delegates: 69