He's ahead in delegates, but less than 200 hardly qualifies as "by far" when he need 1237.
It's a lead though, for now. Might not hold up if the delegates go to a second ballot though, in accordance with the established rules.
200 plus (not less than 200) delegates represents 31% of all the delegates awarded to date and 37% of the votes cast compared to 28% for Cruz.
The lead will grow significantly when voters go to the polls in NY (95 delegates) on April 19. April 26 will see primaries in CT, PA, DE, MD, and RI with a total of 172 delegates at stake. Trump holds a commanding lead in all of these races. By April 26 Cruz will be mathematically eliminated from reaching 1,237. Trump will be the only candidate left with a shot at 1,237.
Might not hold up if the delegates go to a second ballot though, in accordance with the established rules.
That is the only shot for Cruz and Kasich. And if you take Paul Ryan's statement as gospel, the guy in charge of the convention, he indicated that any of the 17 who participated in the process would be eligible including Jeb and Marco.