An ad is not campaigning for, so I suspect the Truth might be somewhere in the middle.
Do you suspect Cruz will be running an ad for Trump in the next few months?
Did Reagan take a pledge to support the eventual Republican nominee, then start violating that pledge?
Did Reagan tell people to "Vote their conscience", with that exact phrase being the battle-cry of the #NeverFord people for months on end?
An ad is campaigning, if it is a campaign ad.
That one campaign ad was not the totality of Reagan’s campaigning for Ford. Did you see this link posted up-thread? https://youtu.be/zbvIo9Lebrc
Ted Cruz is no Ronald Reagan. Cruz has no integrity.