Who are you talking about, Romney or Perry?
Seriously, I believe Newt does have core convictions. One I happen to disagree with is that people who have been here 25 years shouldn't be sent back. But to me, it's a minor disagreement because practically speaking I don't see how any president could accomplish sending them back. 99% of the time I agree with Newt.
And core convictions are nice, but I'd rather have a guy who's RIGHT on most things whether or not they are core convictions, than a guy who's wrong on core convictions like Ron Paul for example, or a guy who's got no chance in heck of beating the Democratic nominee, hmm... Ron Paul's a good example for that one too!
I'm going for the guy I agree with most (core convictions or not) between the top two candidates when my state votes. I prefer Newt, but I'd also be OK with Cain, Santorum or Bachmann if that's the non-Romney that conservatives settle on. Currently my biggest concern is we WON'T settle on one, giving Romney an unopposed path to the nomination.
No one - and I mean no one - is sending 11 million (15 million, 40 million, whatever!) illegal immigrants back home. Sure, you make it harder for them to work here and deny benefits available to citizens to incent them to return. You might deport 10% or 20% of them, but never get them all. A combination of tougher laws and incentive to leave is the key initially.
So what do you do? My two simplistic cents - Secure the border first, and figure a way to slowly allow certain ones earn citizenship (here for a long period, paid taxes, no criminal record, etc.) and incent the rest to leave by making it hard for them to work here. The government will not round up a large percentage of illegals and ship them home. Just isn't going to happen.