Yes, there was a FISA warrant to spy on the Trump campaign.

Some of the details of this (with distortions and Liberal interpretations) are provided by the Washington Post:

https://www.washingtonpost.com/world/national-security/fbi-obtained-fisa-warrant-to-monitor-former-trump-adviser-carter-page/2017/04/11/620192ea-1e0e-11e7-ad74-3a742a6e93a7_story.html?utm_term=.e9bfeb1a04d2

Was this warrant used to monitor the Trump campaign? YES!

The Post tries to make a case that this guy Carter Page was in bed with the Russians. He was not. He tried to make money from owning Gasprom stock. Was he approached by Russian agents? YES. Did he do anything illegal? NO! Was there a justification for unmasking his name? NO!

FISA warrants can be easily obtained, only 0.03% of the requests are turned down. Why? Because there are stringent rules on the use of info obtained under such warrants. Obviously, these rules were not followed in surveilling the Trump campaign. This was not an intelligence operation, but a spying operation on the Trump campaign.

I stand by a previous post that that were two FISA requests to monitor the Trump campaign. One of them was granted.