Trump is the Republican front-runner. He had 457 delegates before Saturday's caucus, and Texas Sen. Ted Cruz is in second with 364 delegates. Those numbers will change after delegates are allocated from D.C.'s caucus. 
The win comes three days before one of the biggest days of the primary schedule in what could be called the second Super Tuesday. 
Five heavily populated states that allocate a large number of delegates vote, including North Carolina, Missouri and North Carolina. 
Ohio and Florida, which give the winner of the state all delegates — the first winner-take-all contests in the primary season — will allot 165 delegates between the two of them. 
Rubio is working for a win in his home state while Ohio Gov. John Kasich is hoping for a victory in his. 
A win by either of them won't necessarily make it possible for them to win the 1,237 delegates needed for the nomination, but it will make it more difficult for Trump to reach that number.