Frankly, while this a pretty forceful speech, I don't see how the establishment former nominee slamming Trump necessarily hurts him. Maybe it does, but I don't really think it will.
The attacks are working; Trump isn't getting the delegates he needs to win the nomination outright, which is the bottom line.
Anyone to insults George W. Bush over 9/11 while praising Putin isn't winning the GOP nomination. That would be like Margaret Thatcher winning the Labour Party nomination.
Stop saying it because it isn't true - Donald Trump is ahead of schedule, not behind.
He doesn't have a majority of the delegates allotted thus far, and Carson dropping out will help Cruz. A brokered convention is still the most likely outcome, though that scenario would produce either a Trump nomination or a walk-out by him and his supporters.