[Kenny]

This explains it:

http://www.msnbc.com/msnbc/carson-other-campaigns-sabotaged-us-dirty-tricks

Cruz sent out emails to caucus workers that Carson dropped out of the race.

[Cats Pajamas]

Carson did suspend his campaign when his staffer was killed in a car wreck. Momentum was lost. But that happened to Carson at some other times also.

[FreeReign]

Fox now reporting that the last 13 Iowa polls had Cruz losing to Trump.

This explains it: Cruz sent out emails to caucus workers that Carson dropped out of the race.

Naw. RCP poll averages had Carson at 7.7%. Tonight he got 9%.